So you are running 12 bulbs total @ 432Watts. I would say that is probably enough light to keep most any coral you choose in the future, what will matter is what depth you place your corals in the tank.
As for timing, you can pick up a couple cheap timers from any Home Depot/Rona etc. The two cords are to split your Actinics from your daytime lights. You can run your actinics 24hours if you choose to, but your daytimes should range from 8-12 hours.
The seller said there is 8months on the bulbs... was that 8 months left? or they had been used for 8months already? I suspect they have been used for 8 months already, which should give you about 4-6 months before you need to replace them. T5's, from my research, should be replaced every 12-14months (I think.. crap, can't remember now.. lol) They may produce heat, there are 12 bulbs there, but I don't think they will produce the same heat as 2 or 3 MH's would. Don't those Tek fixtures have built in fans anyways?
Hope this helps somewhat.