that's a lot of questions that could take hours to answer correctly.
any momentary SPST switch will work for your power button.
for LEDs, most will work with any mobo. however, blue leds usually need more voltage that your mobo can deliver to light correctly. generally one would try an LED first to see if it lights up. if not, then a simple transistor amplifier will light it up:
http://www.vhforums.net/cgi-bin/ikon...t=ST;f=16;t=13
here's a good thread on modding for multiple HDD LEDs:
http://www.vhforums.net/cgi-bin/ikon...f=2;t=1086;hl=