1. Concerning record keeping, talk to your players. Styles differ. It may be that they just find that it distracts too much from enjoying the game. Or that they've never been trained on it. If the consensus is that it's too much trouble for the benefit, institute one or more of the suggestions above (monthly expenses automatically deducted, run out on a "1", etc). If the players are willing to put in the effort, then ask them to come up with simpler ways of tracking the info - and reward the players who do so with extra XP, skill points, or whatever.
For one-shot magic items, such as potions and scrolls, I found that giving each player a separate card for each such item works well. If the character uses a potion, the player hands the GM the card - no forgetting to erase the item, no confusion over just what the potion is, and so on.
2. Feats - this is really up to you as GM. The more inexperienced the players, the more likely I am to allow retroactive changes. Regardless, if you have trouble saying no, put a limit in your house rules and point it out to the players before the first session. Either suggestion above works well: a limit on the total number of times it can be done over the life of the character, or a requirement that the character must have never used that feat.
3. I find that extensive character backgrounds don't work so well before actual play. I require that the players complete a simple ten question ethics sheet before the first session. Then after the first or second session, I ask for character backgrounds. Then, after a few more session, I'll ask them to flesh out something in their background (a 2-page write up on the monastery they studied at, or the pirates they sailed with, etc). By giving the players time to settle in to their characters, I find that the backgrounds fit better and also allow for actual campaign events to be included. For example, a character accidentally shoots a comrade in the back in the first battle - the player decides his bad shooting is why he left his old clan (he shot the clan chief's son in the foot...) For all of this, I give XP, though other rewards work well also. Be sure to reward players who go the extra mile too.
4. and 5. I try to assign homework to the players to flesh out some of this. As I said above, let a player flesh out the pirates or a local monastery. Maybe one of the character's backgrounds says he ran an inn - give the character XP if the player writes up an inn with simple backgrounds on some of the npc's, or merchants who deal with it, or a group of smugglers who use an inn for making deals. Players will often come up with stuff you'd never think of, and you can always change a few details to keep them on their toes. Plus, this makes it easy for the character to know certain things, without you having to explain it.