I know that it can be hard, especially since his father just passed away...I think it makes for a sensitive situation. But while he may not like to, your FI has to step up and put up some boundaries. He doesn't have to be rude or nasty but there are limits! For example, if she's calling at 6:45 in the morning when she knew you got in late, he shouldn't be picking up the phone right away at her beck & call...he can call her back when he's able to. She's doing what she's doing b/c he's allowing it to happen and if he doesn't do/say something, she'll continue to behave that way just because she can.
With the reservations, your FI should let her know that it's out of your budget and have some suggestions of places/rooms she can stay in that are in your budget. If she wants something grandiose, then she should pay for it herself.
Ah! This woman sounds so selfish! Good luck to you & your fiance!