1. A friend cannot have more than one class at a time, you can always attach another class in a "related" fashion (i.e. up on top) but you'll only get that card's upper right-hand resources. It's also a pretty pricey way to get those resources.
2. The personally attached cards (i.e. on the side) do increase your resources when you change them from Alert (vertical) to Busy (horizontal), of course the opposite is also true.
3. The text at the bottom of a fate reading "Technomage" or "Avatar", etc. means that the fate in question is a personal attachment for those classes. So if I have a Technomage "PDA" will be personal (i.e. on the side) versus related (on the top). So many fates are dependent upon classes.
4. The AI (and you if you choose to) can get rid of friends if it plays either "Argument" or "Casualties" (both action cards). However, *you* can also lose friends if your Profile Points get to be too high.
5. You get to an editable deck by winning at least one game against the AI. Of course you have to be logged in as a registered member because we'd have no way of attaching a deck to you if you were just a guest user.
6. The Adventure cards running out is the quickest way to end a game, yes. But you can also run out of deck cards (generally by using a lot of "Plan B" or "Handshake" cards in a row.)
7. Until you can actually set up your own deck it's pretty much impossible to tell whose Adventure cards are whose. You can make some educated guesses as far as which resources are required in order to complete them, for example if you play with Persephone/Avatar deck you won't get a lot of Adventures that require scads of strength to complete.
8. You can view your opponent's played cards at any time, just mouse over them and they'll flip over for a better look. Also you can right click on a card to get a large view of it. To go back up to the opponent's cards use either the arrow keys or if your mouse has a wheel on it, that, and you'll move the view back up to your opponent's team.
9. One last thing, you can also use the menu to call up the log, which will show you each and every play so you can figure out what's happened if it isn't clear.
And in relation to a specific question on how Dooms work as far as Resources are concerned:
The negative cards are Dooms and they do stop some Resource usage. Let's go with your example:
Persephone with Tarot:
Alert Resources= one Magic, two Vision
Busy Resources= two Magic, two Vision, two Knowledge
However, she's also carrying two Dooms:
Traitor- negates one Vision, gives points to a rival copy
Enough- negates one Vision, doesn't allow any more Related Fates
So the two Dooms are negating the two Visions. Always check the upper right corner of a Doom to see what Resource they'll cancel out on you, not all do (for example Dissatisfied).