I will answer your questions in the order you asked:
You don't need to press anything- Just walk over it. Rare guns drop etc-- think of loot drops like in Diablo.
The comp says something on low HP. Armor begisn to regen when out of combat. Depending on the types of armor you have determines how much armor and how fast it regens.
Yeah I thought the pic was a nice touch. I had to escort that lady for a mission.... to my ROOM. GIGGITY!!!
Oh here's your WORLD MAP:
http://img518.imageshack.us/img518/6176/mapmq2.jpg