i may be repeating what others have said, but hey, i got time...

-What is the Kickflash used for, and can i use it my 1200t setup?
you put rom updates, and drivers and stuff in there so you don't have to repeatedly reboot to run OS3.5/3.9/4 rom updates, and to have things like USB stacks available at startup for booting off of.
yes it will work if you have zorro slots, which it looks like you do...
-Can the CDTV use the a500 clockport addon?
yes
-Is there a way to make PCkey 1200 use a ps2 connector instead of the Big Old Din style?
there is a keyboard adapter available. if it does only provide the big din type, then you can use a din2ps2 adapter...
-Can i use two a2090 cards in my 1200t setup?
yes, but the a2090 is a bit pants really. better off getting something bit better
-Is there an easy way to mod the Apollo 1240 to use a 060cpu?
depends. how handy are you with a soldering iron?
-How do i speed up Workbench without adding ppc?
more ram, better CPU, SCSI based hard disk instead of IDE, and/or, a graphics card will make workbench a much more comfortable environment.
-What is the FBAS and Y/C output used for on my Piccolo card?
FBAS? you mean like composite video?
Y/C? as in superVHS?
basicy video output to a standard TV display device.