75% of Steem inflation goes to authors and curators on posts and upvotes while 15% is given to Steem Power and 10% to witnesses. This means out of the 9.5% current total inflation, about 7.1% of all new Steem "printed" is given out to users making posts, comments, and upvoting through curation.

Obviously, by "Steem printed", you mean the Steem inflation (9.5% of the total Steem already released). So, 75% of the Steem inflation is the same as 75% of the "Steem printed", which is roughly 7.1% of the total Steem released over a year.

Posts cannot be deleted after 7 days but can be edited indefinitely.

Yes, posts cannot be deleted after 7 days, but No, currently posts cannot be updated after 7 days. At least through the steemit.com web site.