I've been looking at this (diagrams below) and finding a few non trivial questions. The line I'm interested in is where black expands on the queenside after white doesn't take on c5 early. 

Now the main (only really) line of this currently on my database seems to be 8.. cb. Everyone in practice seems to have automatically recaptured there with ab there but my sundry computers point out that white can just go c4 instead:

 

Doesn't this just give white a bunch of extra options like a Q on b3 not a pawn? It really doesn't seem comfortable for black to me, and at best is some non trivial extra options for white such as Qxb3 not ab.
(well unless you can snatch a2, but that doesn't seem at all healthy.).

Now obviously the historical line here has been to go 8 .. b5 when 9 b3 Bb7 got stomped on rather convincingly by Geller. What seems to be much less clear is the piece sac below, which I'm not at all sure about:



Not even sure if black should take on c4 there or not. Very messy and it seems somewhat like both sides are avoiding it (with white going 9 c3 the couple of times they've got this far.).

Any recent sources, analysis or ideas for either of these? Obviously black will always have 6 .. cd but thats probably just not as interesting.