"What wattage PSU should I go for? Will the higher end ones suit me?
It depends on what hardware you need to run - use this Newegg Power Supply Calculator to find out.
Is it worth having a LCD gauge on the front for temperature / system time / fan speed etc?
No it's not worth it. It's more for overclockers and vanity reasons.
Is having a Perspex window good for anything beside visuals?
Yes, it's useful to occasionally glance at it, and then realize that your CPU fan has broken down.
Will most cases fit any type of motherboard?
Big cases will fit all motherboards, small cases will fit small motherboards. Look out for your motherboard size, usually it says ATX, or mATX, etc. Find a case that you know supports it.
Are tool-less designs really that great?
Definitely if you are going to tinker with it often.
Do all cases suit a water cooling method?
Depends on your water cooling methods - actually, most cases would need a bit of tweaking/machining to get water cooling solutions to work.
Do the cases with a front door to access things get annoying?
It's a personal opinion, but I hate front doors. Just give me the ports or CD-ROM already, dpn't make me need to waste energy opening the door first to access the front ports, and I know many front doors get jammed when the CD trays open.
Do I need more than one fan at the front and one at the back for the case?
Depends on whether you are overclocking or not. For best air flow, one in front, and the one at the back first. If temperatures don't seem right, increase the number of fans (bad), or increase the quality of the heatsink. Remember, more fans = more noise.
What are your experiences with tasteful mods?
Worth it if you are going to display your desktop out in the open for everyone to see, totally not worth it if you are going to chuck it behind the table.
"1) Depends on CPU and video card mainly. I'm happily running an E5200 + passive-cooled 4670, not seen it pull more than 200W. PSU is a 80%+ 380W.
2) Not in my experience. Maybe if you overclock and need to keep a close eye on things.
3) You can see when you need to dust inside, but again, not in my experience.
4) ATX ones will fit both ATX and mATX, but mATX will only fit mATX.
5) Convenient if you upgrade every so often. Not a deal-breaker, but nicer to have it than not.
6) pass
7) Yes, if you use the CD drive at all.
8) Depends on what's inside and overclocking, but under normal usage, no.
9) None. Can't see the point, I don't look at my case or take it anywhere for anyone else to look at. Quiet is more important for me. Big, low speed case fans, passive heatsink on the vid card (NB they can take up more room, so a low profile case won't do. As I found out.) and a good solid construction to eliminate vibration from drives.
