Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
I have 2xleadtek 6800gt's. for them to fit into my DFi i had to remove the plastic covering and one of the rear copper plates. I understand that the DFi has the same spacing as an MSI. I can email some pics if you want.
The cards will do it, although you might have to modify the cooling solution to make it happen.
You can either get some reference coolers, or simply modify the stock ones. Although in case you ever have to RMA one of the card's I'd suggest keeping at least one unmolested stock cooler around.