New to Discus, Help needed!!!

ok i have decided to finally try my luck at keeping discus, now i just need the helpul advise of discus keepers to help me set up my discus tank

I have currently a 40 inch wide tank, by 18 wide by 24 high, its an unsual size i know, but its the biggest i can fit into my bedroom, its an aqau one curved glass tank. This is a display tank, it will be planted but not too heavily, so ........

will i need a Co2 system?

Anyway, what kind of filteration would i need?

im a big fan of the eheim filters, but i have since looked at the hydor range and they look impressive.
Would i be better off with 2 smaller canisters or just one large one?

What kind of UV stereliser would i need, internal or external, what brands could be recomended and how much?

Should i use an internal heater or external hydor heater?

Money is not really an issue, i just want quality equipment thats low maintainece.

And finally, this is my first time at keeping discus, i have kept every other fresh water fish you can pretty much think of except discus.

How many discus should i start of with?
i was thinking 2 fish to begin with and then adding another 2 later on, but i have read in this forum, the fish do better in groups. Any help would be much appreciated

thanks in advance

nick!