1. no idea :/
2. it's saved in data/init/embark_profiles.txt . but these should remain even if you delete a world.
2a. not that I'm really aware of. It's really up to personal preference, here's the gist of what I usually use:
-Proficient Miner / the rest in negotiator / appraiser / judge of intent (this usually becomes my leader
-Pro Miner/Brewer
-Pro Farmer, rest in tanning/butchery
-Pro Cook/Carpenter
-Pro Mason/Mechanic
2x -Pro Wrestler, Novice ambusher (free leather armor + crossbow), rest in Shield user (these guys are my watchdwarves, to take care of any early animal threats/thieves, and hunt/do oddjobs in their spare time.). I make them wood or leather shields early on.
items:
about 40 in booze (split over the four different kinds
1 each of all the cheap kinds of food (you get a free barrel with each type of food, mmm barrels)
10 turtles or cave lobsters (for shells, a common mood requirement, make sure you set them not to be cooked)
2-3 picks
1 axe
5 cloth, 5 silk, 5 leather (more Strange Mood insurance)
4 or so ropes (animal restraints, wells)
18 plump helmet seeds (i use a 3x3 farm, this give me enough to fully harvest it twice before i need to start making booze to get new seeds)
5-10 silver bars, for making weak silver sparring weapons, also good if you get a mood and are low on metal
a few dogs (don't bother with hunting dogs, but chained dogs make decent thief detectors, and they'll provide some meat and leather if the need arises)
one cat for pest control
might be forgetting something but that's most of the necessities. I always buy an anvil later, as I usually haven't even struck metal by the time I buy one.
3. you can't directly check more than one search result for a location. it's annoying and will eventually be changed, right now you can use the trick phazer posted, or slightly edit your search parameters and try again.
4. yeah, the river (or brook) needs to be within your selected starting area, or it won't appear on your map. many maps that aren't too hot will have murky pools, which will slowly refill from rainfall, but for a big water supply, you need an endless source (river, underground river, or aquifer (although aquifers are hard to deal with and i would recommend avoiding them when just starting out))