Mac Pro :: Upgrading From The 4870 To The 285?

I need some help getting some facts straight. I am considering upgrading from the 4870 to the 285. It's a fine idea except that the 285 is very expensive, but at least I could try and sell the 4870 and maybe get $300CAD for it. Then I thought, what about just getting a second 4870 and crossfiring them?

I have read through a good 3 or 4 threads on these forums about powering the second card, flashing PC cards and working with crossfire... that was a freaking long 3 hours of reading non-stop.

So I have these questions which I hope someone here can answer with reasonable certainty.

1) When doing crossfire, do the cards have to be very similar for them to work? If 1 card is 512 and the other 1GB will there be any advantage over just getting a card with 512?

2) If other cards of the same family work, would a crossfiring of the apple 4870 with a 4870X2 perform similar to 3 X 4870 in crossfire?

3) Could someone explain the cables and/or hardware needed to power the second card from the second optical drive slot? I think the best way to go is 1 cable from each card to the regular spot and 1 cable from each card going to the same connector in the optical bay.

4) Apparently 2 X apple 4870s don't work with crossfire. But does this apply to combining an apple 4870 with an unflashed PC 4870?

5) I thought I read about some attempts to modify the ROM of the apple card to enable crossfire with some success. Is that true and if so where is this ROM and does it negatively impact the apple 4870 in OSX?

6) If have read in the past (I think with the PC 3870s) that if you connect a second unflashed card to an apple card with the crossfire link that the card behaves in OSX (doesn't spin it's fans wildly). I don't need it to do anything in OSX except not blow up, I only care about it working in windows. I'd like to avoid flashing the PC card if I can.