Runemaster5000

Greetings,
I'm looking for a new chassis, full form factor with lots of 5.25" bays. I'd like to go full water cooling with it, and I mean everything, RAM, CPU, graphics cards, sound card (if needed), hard drives, bridge chips. But I have a couple of questions.

If I were to cool these core components would I need to have fans for everything else? What about the motherboard itself? Reason I'm asking is because I would like to seal the entire case from the outside atmosphere. I don't like dust getting into the case and it's very annoying to swap out parts and find out there's caked dust on everything.

I have thought of installing filters over the fan intakes, but then I find myself asking even more questions. How long do the filters last? How well do they work? How much do they impede airflow?

If installing filters over all the fan intakes DOES eliminate the dust problem, what then is the performance increase in liquid cooling over air cooling and is it enough to warrant the hardware costs? Because the biggest reasons I'm looking at liquid cooling is because I'd like a much quieter PC and would like to be able to seal the computer. I've also heard from many that there is no difference in fan cooling and liquid cooling, but I know there is some difference.

Couple of more questions:
- What's the point of putting the power supply on the bottom of the case? I've seen a few computers lately that have been configured like that. I would think the heat from it would pose a problem to the components above it.
- Final questions: What would be a good sealant to use for all the cracks, holes, and other areas in a case? I'm thinkin' hot glue myself...
- Do the new Solid State Drives generate much heat?