1) For the first one make a trigger doing- Every (time amount) Add x(gold amount) to Player x Current gold
2) Make a trigger that sets a variable for the player to +1 for each kill, then another that has its event as Real value (variable) becomes equal to 20 Defeat player x with message (you be dead)
3) Under the units make their bounty to whatever you want it to be, then have a trigger run on init that does Turn player flag Gives bounty On for Player X
That should just about cover it all, if you need more help PM me.
