Not a problem. Check out my Extort deck on my profile, I built it for the cost of a $20 Orzhov Guide deck and then selected singles from TCG Player, about $22 worth. It's been banned from multiplayer games with my friends though, it's too vicious.

Yes and yes to your questions. I have 4 of each in my Extort deck. Also of interest in the Vizkopa Guildmage, which for 3 mana invested can double your extort damage. In a multiplayer game, it is especially vicious.

Vizkopa Guildmage: 1C1B1W: Until end of turn, every time you gain life, each opponent loses that much life.

So extort for 5 and deal 10 damage. You don't gain the extra as life, but it's ruthlessly efficient and can help you put serious pain on enemies even if you don't have many extorts on the board.

Pair that with Exquisite Blood (Enchantment, every time your opponents lose life, you gain that much life) and you win instantly as it is recursive to infinity.