Hallo!
c) 75% - 25% is the answer we all know, however I've read that it really depends on a lot more factors, it's not as clear as that!

I read a post from @themarkymark about this, in it he says:

after looking at 7 different ones [posts] (I looked it more like 100, but I didn't want to bore you) we see the actual curation rewards range from 12.36% to 20.6% but never even close to 25%. In fact I've found some that are in the 6% range with lots of votes.
We can assume larger whales and popular posts curation rewards will be less than smaller authors with fewer votes. We can also assume most people self-vote their post at some point before payout.
Although there is no clear answer what the number is, if we just average the min/max we will get 16.48% average curation rewards per post.

If you wish to read the complete post you can do so here, it is a great post to read as this is a very interesting subject, his findings come really close to the numbers I've experienced, both with my smaller posts and my really successful ones! :)