1) Yes, applying does not guarantee a spot in the post-bacc program. If I have read correctly, around 40 people apply and only 10 get accepted. I also got invited to apply for the post-bacc program and by looking at the application it looks as if they mainly look at two things.. 1) your ability to write a convincing personal statement, and 2) if you're disadvantaged or reside in an underserved or rural county.
2) I believe the program is completely paid for. If you go to the website that was posted on your letter to find the application, browse around that a little bit, additional information on the program can be found.
3) You are only expected to take 12 credit hours for both semesters at Lawrence; therefore, if you can manage to find a job, I'm sure you should have plenty of time to work also.
4) My interpretation is the first summer, and then the fall and spring are all at the Lawrence campus; however, I may be mistaken.
5) It was mentioned that they supply housing. However, I am unsure if the housing they supply is just dormitory housing or what. I would prefer not to live in the dorms, so if I do, by a long shot, get accepted, I would try and find an apartment.
I hope this is of help. The answers are kind of vague but it's the best I could provide at the moment. Congrats on receiving the application to apply for the post-bacc program, it may not be an acceptance yet but hopefully it leads to that.