1) vendors:
I second the ones you already listed. I'm not really partial to any vendor. Actually I really don't care. Just make sure they have good ratings on resellerratings.com, others have bought from them in the past, and they actually have what you want. There are a lot of little shops that randomly have popular items. Not fair to make a list when you can't include all those
2) biocide:
The kit you bought comes with swifty's coolant. IIRC, someone else please back me up, thats an all in one package. Glycol + algicide or whatever. You don't need anything else. If you were using distilled + antifreeze then you should add some iodine.
3) coolants:
blood red looks kool
Personally I'd never buy "pc water cooling" coolant. Waste of money IMHO. Plenty of different colors of AF. I'd rather use propylene glycol as opposed to ethanol. Propylene is the "environment safe" kind with pretty pictures of dogs and birds on the bottle. Course I've never found non-green
4) tubes:
What kind of tubing you should use depends on a lot of things. What components you have(all 3/8"?), how much space you have to work with(very crammed micro-atx?), how much do you want to spend, etc. 3/8" is generally fine. Sure there will be some lone scenario where a guy's pump just dies at some specific pressure and the added resistance 3/8" ID tubing gives over 1/2" kills it. But with the mcp355 you have IWWAI. In terms of brand look for tygon r3603. r3600 I think is the black stuff which looks pretty kool.
5) pumps:
There is a huge thread on pumps here written by the master, Cathar. To make a very long and involved story short the mcp355 is a great pump. Even with a CPU, GPU, NB block that pump would be fine. If you are bored look up the mod to the MCP350/DDC pump(same casing as the MCP355/DDC+) to increase the inlet size.
6) radiators & cooling blocks:
Having all copper/brass parts simplifies things. Contrary to what people usually blurt out having an Al rad or block is fine. That just requires you to be anal on coolant. Namely the ratio of glycol to water has to be higher. I ran a copper block and a copper rad on a PC for a year plus, just had 20% AF and 20% distilled and it was fine.
Unless you are looking for a weird rad(huge car rad/oil cooler or zalmans reserator) its pretty rare to find an aluminum rad that you can actually use dimensions wise.
As for block performance you can sift through this forum. Tons of great reviews. Theres even a interactive performance graph on procooling.com that lists a lot of popular blocks.
8) cooling blocks:
DO NOT LAP YOUR SWIFTECH BLOCK!!! The reflective quality of blocks means 0. Its a good guesstimator but what you should be concerned with is how flat it is. Swiftech's machining is top notch. I don't think anyone makes blocks as flat as they do.
If you make your own blocks or heatsinks for other stuff read up on lapping. Again, with lapping your goal is to make the surface very flat, not shinny.
Definitely feel free to ask any questions at all.