Snoekie, in answer to your questions:
1) Yes, the guilds are the only place to identify items (the Armory, actually, I think, and it can be costly.) However, after the 2nd Valeia Temple Guild quest, you should be at 3rd level Temple and be able to acquire the "Ancient Lore" trait. After than, you can start training in "Artifacts" skill and be able to identify items. The higher the level in the skill, the more expensive items you can identify.
2) Check and see what they sell for. If they don't sell for more than 50 GP, not worth it. Just sell them. The ones that sell for under 10 GP are likely the "rusted" varieties. Only ID "interesting" items...like Ankhs, etc. BTW, you can equip any item without ID'ing it...just save beforehand in case the item's "cursed" (like those cursed daggers so prevalent early in the game), otherwise you'll REALLY have to pay out the wazzoo to get the Temple to remove it!
3) Try buying arrows and selling them back. They sell back for higher than what you bought them for...an easy "legit" way to make money.
4) Don't buy armor. Use what you find. Later, there'll be a good way to make more money. Put your money in guilds and skills training.
5) 10-16-33-42-43-49 (just kidding!)
-Sazerac