MRF generally goes after the the best players who can bring international exposure for the brand name. When Brian Lara was sponsored by MRF, they were making a big push towards selling tyres in West Indies. If MRF is planning to expand business in SA(which i am just speculating) who else can better promote them if not ABD !
AB has a huge recognition in IPL as well and currently he is whacking the indian team in SA's tour. I am quite sure AB would be paid a huge sum - 500 to 600k seems a good bet.
Guess AB's bats might come from SS with MRF stickers. Softs would probably come from SS or BAS, given that Kohli and Dhawan's gear bear striking resemblance to BAS/SS gear. For all we know AB's Kook gear might have been a SS labelled as Kook !