Mtg combat questions?

You would win. The first strike would save you.

Since you have first strike the combat phase gets a second combat damage step (510.5). During each of the combat steps the players announce combat damage and then the active player gets priority to cast spells or abilities (510.4) and the rules for winning and losing that they if a player drops to 0 they lose when priority to cast a spell is granted to any player (104.3b). Thus you would win before you start the second combat phase because your opponent is at 0 without a Angel to keep them alive.

Rule 104.3b states: If a player’s life total is 0 or less, he or she loses the game the next time a player would receive priority

Rule 510.4 states: Fourth, the active player gets priority. Players may cast spells and activate abilities. (NOTE: Fourth is after combat damage is assigned and and trigger abilities are on the stack ... check out the link below for the rulebook to see 510.1-501.3)

Rule 510.5 states: If at least one attacking or blocking creature has first strike (see rule 702.7) or double strike (see rule 702.4) as the combat damage step begins, the only creatures that assign combat damage in that step are those with first strike or double strike. After that step, instead of proceeding to the end of combat step, the phase gets a second combat damage step..

As for your multiplayer question: You can't force someone you are not attacking to block.

EDIT: I used an older rule book for my references. I changed the numbers and wording to reflect the newest book. The outcome is still the same though. http://www.wizards.com/Magic/TCG/Article.aspx?x=ma...