As for power consumption, get a meter (such as the P3 P4460 Kill a watt) to see how much power your rig consumes _when_ it mines.
I use this exact meter, an HD 6870 adds on about ~160 watts when it is mining vs idle(clocked at 985mhz core 300mhz memory).
Personally, I use cgminer, but I like the ability to tweak the command line options quickly. GUIMiner works just as well.
For pools, I use Ars as my main - they take transaction fees and beyond that all donations are voluntary. It's SMPPS based on current difficulty. (1/difficulty is payout per work accepted - minimum balance to withdraw is 0.01, minimum auto-payout is 0.5)
My primary failover(not sure if guiminer lets you set failovers? haven't even checked) is luke-jr's which you connect to with your wallet address, and get payouts any time your balance reaches 0.67btc(I think). I believe the style of payouts is similar to ars. I've not yet actually had enough failovers from ars to build up enough for a payout.
If you haven't already, check out https://en.bitcoin.it/wiki/Comparison_of_mining_pools
As for command lines, once you figure them out, it's easy to make a .bat file(windows) or a shell script(linux) which will run your command line options for you. Just be careful if you try to overclock on a command line, one misplaced 0 and you'll (at best) force a gpu hardware restart, or (at worst) kill your gpu permanently, and possibly the PCI-E slot it was connected to.