Okay, finished my first bot game, started out terrible but I think I pulled it together a bit better by the end of it, but naturally I have some questions again.
1. I noticed people claiming lanes, I knew they do this, but is there any rhyme or reason to this or is it more "I think I'm better then all of you so I'll take mid and throw a fit if you don't let me"?
Someone already explained what the usually roles/lanes are, but I felt that I should explain the logic behind the meta-game so you know why things are the way they are. Prepare for walls of text.
First off, experience is shared between champions when an enemy minion is killed nearby. Therefore, having just one champion in a lane is preferable because they will level up faster. However, you've got a choice of 5 champions and three lanes, so you're going to have a 2-2-1 setup. However, a 2-2-1 setup doesn't take advantage of the jungle creeps. Sure, you can step out of your lane for a moment and grab them, but you won't always have that opportunity. Another thing of note is that jungle creep kills do not grant experience to surrounding allies, only for the killer, and the experience, given that the creep camps take time to repopulate, isn't very good. Therefore, you can get a 2-1-1-1 setup, but going for three solo lanes and two junglers isn't optimal.
From there, some logic goes into deciding who goes where and why. There's two solo lanes, a jungler and a duo lane. There are two very important locations on the map: Dragon and Baron Nashor. Control of those two locations are absolutely vital, but because Baron Nashor is so difficult to kill, even with a team, it's usually only a concern for late in the game. Therefore, control of Dragon, which is toward the bottom of the map, is essential. That means that the duo-lane should probably go in either mid or bot lane so that there will be more people around the area of Dragon to either take it or stop the enemy from taking it by fighting them off or stealing it.
Another point of consideration is the relative lengths of the lanes. Mid lane has the shortest distance to the tower from the middle of the lane, while top and bottom are both pretty distant. That means that mid lane is ideal for champions who are very "squishy" or who can be killed very quickly due to health. Attack Damage Carries (ADC), Ability Power Carries (usually only referred to as AP champs) and Supports are the types of squishy champions. Previously (Season 1 I believe), it was decided that ADC champions would go mid. Supports would go bot with either a bruiser-type champion (Tanky AD) or the AP champion. However, synergy between a support and an AP or a support and a bruiser is not ideal. Another point is that ADC champs are not very mobile: they rarely have abilities that quicken their movements and they lack hard crowd control abilities (CC, "hard" referring to stuns, roots, taunts, fear and suppression. "Soft" CC refers to slows, charms and silence) to stop enemies. Even with the relative safety of mid lane, ADC champions were still quite vulnerable, and actually leaving their lane to support control of Dragon was dangerous due to just how vulnerable they were. AP champions, by contrast, often have hard CC abilities as well as abilities that support their movement. Because ADC champions are so squishy, they need the extra help and so the meta shifted such that AP champions went mid and ADC champions went bottom with a support.
AP champions could also theoretically go top, and sometimes they did, but due to their high mobility and high burst damage, their position in mid is ideal as they can leave their lane to gank enemies or to exert control over map objectives, like Dragon. Therefore, the question is "What to do about Top lane?" The answer is basically "Put whatever that can survive and benefits the team up there". You'll often see bruisers up there, but you may also see Swain or Kennen. Usually the best fit for top lane is a champion that has considerable health, health-gaining or health-stealing abilities, or good chances for an escape given that the lane is so long. Essentially, the champion needs to survive in case things suddenly take a turn for the worst. Since top lane doesn't have to care about map control until after lanes become somewhat meaningless beyond tower control and minion pushing and team fights become more frequent, mobility isn't a big consideration, so someone slow but bulky is often chosen.
The last consideration, then, is jungle. Jungling before level 15 is often very painful, because jungling is heavily reliant on masteries and runes. 15 isn't that special of a summoner level, it's just a bit more reasonable than any previous levels. The ideal level is of course 30. The jungle role basically takes the same logic as top lane: you need someone that can survive in the jungle, as opposed to lanes all of that damage is directed to the jungler. This means lots of health and/or armor and/or health-stealing or health regeneration. A bonus is having a champion who also has movement abilities. For that reason, you may find a very squishy champion, such as Shaco, ideal in the jungle as he can offset damage to himself with his trap boxes and has an invisible flash ability, useful for ganking lanes or surprising the enemy jungler.
What you end up with is the standard solo top, solo mid, duo bot and jungler. Many attempts to break that meta-game match-up have been made, but they require trust and teamwork. For example, while 1v2 would grant the experience advantage to the solo champion, two champions are very dangerous and can "zone" the single enemy champion, which means that they get in that champion's face and make them back off from the range of gaining experience, effectively turning the situation into a massive disadvantage. For this reason, sometimes the ADC and Support duo will go top, forgoing control of Dragon but effectively shutting down one champion of the enemy team. It's an obvious trade-off, because a solo-laner will have to take bottom lane and will be in the same position, so it's usually done with the intention of picking three champions specifically for it: an ADC and a Support that can effectively shut down an enemy at top and a solo laner to go bot that can survive a 2v1 situation. Also seen is sending assassins, such as Talon, to mid, as they often have the same benefits as AP champions but often effectively shut AP champions down. Alternatively, you might see bruisers or other tanky champions like Nunu being send to mid, as they can survive the punishment of the enemy caster and force them from the lane. You may also see a team sending their support to mid with the intention of keeping safe and healed up while their AP champion and their ADC go bot in what is referred to as a "kill lane": massive damage early that can zone and/or shut down the enemy lane. Or, for the same reason, you might simply see a team forgo a support and field two AP champions with the same intent. However, in every case, the team needs to be on the same page and all understand what is good and what isn't good against a match-up, so it is rarely attempted and often doesn't work out.
The tl;dr (although this is missing a lot of important reasoning stated above):
- Bottom lane is for Supports and ADC for survivability and more control at Dragon.
- Middle lane is for AP or Assassin champions for survivability and potential burst damage to steal Dragon.
- Top lane is for tanky champions, such as bruisers, or for champions who can escape in case things go wrong and the lane is so long.
- Jungle is for higher level summoners who can get the necessary runes and masteries, fielding champions who can weather the damage taken from jungle creeps.
- This setup is considered standard, although with knowledge and teamwork, it is possible to take advantage of the system, but it is very risky to do so.
Hope that helps!