There are differing theories with water changes. With skimmers and newer filtering techniques/technologies, it's not AS vital as it used to be, but it still plays an important role in nutrient export, mineral import, and toxin dilution.
I would do 20% every other week over 10% every week - not only will you be more likely to do it, since it will be a chore you half to do half as often, but statistically, it's a more significant impact. (Since that 10% the 2nd week will be changing some of the "newer" 10% from last week)
I always make about 10% more than I need, just in case I spill some. +1 on little_fish's technique, definitely let it sit overnight. Invest in a good refractometer -way better (IMO) than a hydrometer and will save you LOADS of trouble.
I mixed mine in a big rubbermaid next to my tank with a spare powerhead and heater. If the temp is +/- 5 degrees of the display tank, it should be good. Also try to match pH using pH up/down. To fill the rubbermaid, I'd use 5 gallon jugs and count how many I filled the rubbermaid with. Then, when draining the tank, I'd just drain that same amount of 5 gallon jugs. To keep pH balanced, I can't recommend Seachem's Reef Buffer too much - it's easy and painlessly helps you keep your pH stuck at 8.3
liveaquaria.com has a great list of fish and their temperaments/limits. I really like talbot's damsels if you can find one. Open water fish, not aggressive like their larger damsel brethren, and very beautiful.