Sometimes a bay res can produce quite a lot of vibrations in the chassis too, and they can be quite hard to dampen. A lot of them are fine, but you get ones which are noisy even if they're the same model.
The tubing and fittings are pretty simple really. 99% of the fittings on the market have the correct G1/4" thread, so you only need to worry about the size of the tubing end.
Compression versus barb fittings is a purely aesthetic personal choice really. Compression fittings are very secure, and often a little bit more expensive. With compressions you need to make sure you match both the inner diameter ID and outer diamater OD with the ID and OD of the tubing, whereas for barbs only the ID is important. Barbs are also secure, and even moreso than normal if you get slightly smaller ID tubing than the barb size (a common pair people use is 1/2" barbs, and 7/16" ID tubing).
I've always used Masterkleer tubing, and never had any plasticising issues. The size of tubing doesn't really matter (obviously you need to ensure you get appropriate fittings) but in terms of flow/performance there is little difference, so it's an aesthetic choice again. I think that 1/2" OD tubing size looks nice. Any smaller looks too skinny to me, and much larger looks too bulky, but again this is personal opinion.
You can either get premix coolant, or make your own. I've always used premix because it's more convenient, and it's easy to find a colour I like. Making your own is usually cheaper and you can do it in large volumes, and simply involves deionised water, biocide, often a killcoil somewhere in the loop, and dye. Premix includes absolutely everything you need, and is ready to go right out of the bottle.
If you have acrylic parts, avoid any coolants containing alcohols - that is, any chemical with the suffix "-ol", such as ethanediol. Alcohol degrades acrylic over time, and causes cracks and fractures. I've had first hand experience of this using DP Ultra with an EK acrylic reservoir, and it developed a very slow leak and needed replacing. Upon close inspection there was an incredibly fine crack that had appeared going up the side of the reservoir.
