First of all: are you from Mortal Online? Anyway about your questions.
1. I dont know too...I also would like to change my nickname in game but its ok for.
2. Yeah they will die except for dragons. They only die forever if they are above lvl 7. If they reach lvl 8 they can be killed and looted (you earn the same amount of crowns that you spend to buy it). TO heal your units you must have some healer and enter in view mode just to heal, or go to a ally city and pay for some heal or build a fortified camp (units will rest there and heal).
3. Building build buildings... I get confused. Well Im playing as an elf and builded all buildings. im not sure how humans works but only walls for me needed upgrades first.
4. Your cap is 12000. You cant storage more than that. A solution is to set armies and give to them some resources; try to spend on armies and do a lot of fight to loose troops and rebuild armies or simple keep in mind that you will loose those resources. THe thing here is that at the "end game" we get rich and there is not much things to do with all resources.
5. There is no IRC channel as far as I know (now I have 80% of sure you came from MO). But sometimes GMs log in game and use the games channel, also they can answer you here. I think there is no need for IRC since there is a channel that works fine in game.
So hope that I helped you and be welcomed ^^
Anything add me in game (aramsm) and lets do some fights together.