[Ducky]

Yes, you need an iLok for your Plus plugins.
Which two? What do you need?
I upgraded 2 Digi LE products so I got 4 of the 5.
I cannot upgrade to 7 on my OO2 due to Waves' WUP extortion so I loaded the 7.0 on my MBox system.
You can download pre-V7 Plus plugins if you want to stay with v6.9 and seem to work just as well.

DINR and Smack is a good combo if you need a compressor; pultec is nice if you want a tube emulated EQ. Unless you really need to play with effects, Synchronic is more of a toy. If you like messin' with guitar emulators, maybe Slightly Rude will do some nice things (that's the one I didn't get). Do you have a noise reduction plugin already? Been using DINR to scrub all freq's below 200hz and above 10khz on certain solo tracks. Works like a charm. Better than EQ'n them.

If you are divided about what to get, demo each of them. You will get a temporary license assigned to your iLok account to try them all out. Again, you don't need to upgrade to V7 to try these. Just install the previous versions of the plugins.

If I read things right, V7 sessions are not backwards compatable, but should be forward compatable. Haven't tried this yet.