This fits in well with your other question about the # of properties that can be financed as some of the same lenders wll be used.
You have a lot of great questions here that will require some lengthy explenations. You may be better served by having a full conversation in which you can also answer some important qualifying questions.
A couple quick short answers.
There are several types of rehab loans ranging from your local bank, conventional lender, and hard money. You may want to look over the last couple posts about these.
Generally, seasoning issues will not be a problem.
If you have working capital, I would avoid hard money if you can. It is expensive. You will probably run into a max # of properties using your local bank, but you will not know until you ask. Another big question when it comes to rehab loan other than it being investment property is are you going stated or full doc? Lots of conventional lenders that do rehab loans, won’t do stated ones although I do know of a few that do.