There is no way to go back and do old rounds to get previously missed dope. Because of this, if you miss one you'll be less powerful and probably miss more. Snowball effects like this should be avoided when making a game.
Yes but the computer can use Leonidas from day 1, and it'll effectively rape any card in your deck. Also a bug: if the enemy uses berserk and you use the card that removes all helpful effects on an enemy, that cards attack and defense goes to NaN, and works as zero. You then get NaN gold... which works as infinite gold for your deck.