Should certainly hope so re Jack. Given his rankings jump since winning his first title a couple of weeks ago, he should be close to being seeded. But I can never remember if entries/seedings are based on ranking at time of entry or ranking on the week before the tournament.
So in theory, with a big rankings riser, you can have someone whose entry ranking doesn't get him into the main draw, but if it had he would have been seeded based on his ranking the previous Monday.
You do get occasions where a qualifier is seeded in the main draw. This is usually with a late / WC entry to qualifying, who really always was relatively highly ranked, but could happen in the big rankings jump scenario.
Yes, CD, WR 1229 for entry into MD, but once he's in, WR 777 for seeding.
I believe for futures ( and most other tournaments, I think, but not such as Slams ), the entry list is based on the rankings 3 weeks before the tournament start, i.e. theoretically 30/06 here ( actually 23/06 because no new rankings that Monday ).
So: deadline 3rd july. Hence, rankings from 30/6 (i.e not the new ones on 7th july, which is when Jack jumped up - so to speak). But no rankings on the 30th so rankings from 23rd July, when Jack was still way down.