I have several questions:
1. Leadership skill is gone... it is used to increase max. number of lancemates and shared XP in GH1. How do I get more lancemates in GH2? New lancemate slots are earned by doing quests.
2. Is there a way to increase stats in GH2? I can increase stats in GH2.
3. Is the amount of XP required for a new talent different from GH1? (I haven't reached 10K XP in GH2 yet)
4. What places do you suggest a new character to visit to train up?
5. Are the good early weapons/mecha from GH1 still good in GH2?
6. Is there anything I can do about my lancemate jumping/flying and crashing all the time? If I don't give them jets they won't be able to fight with me in space.
I have 23 renown and what seems to be the main quest owned me pretty hard. I have one lancemate, and both of us are piloting Ice Wind, with only body armor and some medium range weapons.
1. You have a very limited number of lancemates. IIRC you can have 1-2 to start, 1-2 from quests, plus 1 from a Talent.
2. Last I knew, XP-related stat boosts were restricted to 10. Your initial stats plus 10 additional points (1 for every 5000 total XP you gain) are all you get, barring cybernetics. IIRC every 4th point of Ego allows one cyber mod without penalties. Any more than that and you'll forever be fighting health problems.
3. No clue.
4. If you can survive personal scale combat, buy yourself a sealed spacesuit and visit Cayley Rock. The caves are a decent place to grind for your first few talents/stat boosts. Don't delve too deeply, though.
5. Pretend you've never seen the equipment and mecha before. The stats and mechanics have changed a lot. Also, mecha engineering has harder limits now, so you have to optimize rather than add everything you want (kitchen sink included). It's still very powerful, though.
6. High piloting skill will let them avoid damage when falling off cliffs. The jumping issue is best solved by giving them enough thrust to fly instead of jump. Spaceflight jets are all you really need, and you
do need them since so many battles are fought in space.
I think the main quest has renown-independent difficulty, so you should probably put it off for now. Train, get better equipment and retool your mecha, and gather more/better lancemates. You should be able to swap lancemates at any time (provided you've earned some), and with the right Talent IIRC your Friends can join your lance (any NPC who likes you enough will become a Friend).
Learn and pump the Initiative skill ASAP. It makes a huge difference when you're limited by weapon speed (and number of weapons) rather than your own speed. If you don't have a free skill slot, either accept the XP penalty or find some way to boost Knowledge (new skill slot every 4-5 points IIRC, but I don't know if cybernetics count).
Also, don't neglect Mecha Engineering. Nearly all stock mecha are deliberately flawed. Just rearranging their default loadout often yields an extra MV/TR point, and that can help a lot. Mounted/held gear (esp. heavy weapons) have a lower weight penalty than installed ones. Some mecha have lighter, heavier, or better armored limbs than others. Some armor is lighter than others, including mecha-specific armor that may or may not have generic names. Nearly every chassis has small modifiers like that.
Also, both enemies and stores sometimes have modified/themed mecha with a random selection of nonstandard, and sometimes quite powerful, gear. You'll recognize them by their names; things like Steel Dragon Buruburu or whatever.