hrm, We all learn to become spies during this time. You will get better at it as you go along. Right now, he thinks you are stupid and wouldn't think of looking at receipts and bills that are coming in. He's relying on you being the person you've always been and not thinking about it and yes, he's hoping that he can gaslight you along the way to believe in him and that he would never hurt you in any way. When they are in mlc, they are the exact opposite of the people we loved and knew, therefore, you are going to have be on your toes and observe and listen to what he's saying and watch his body language...it's a dead give away at times.
You handled his birthday in an excellent manner. The reason he felt he couldn't accept any gifts from you is because he's riddled w/guilt. That's the way they operate all of the time when it comes to gifts, cards, etc. If you hadn't gotten him something, he would have made a comment at some point about it.
As for the fencing to keep the bunnies out, he knew you needed that fencing, but he got rid of it just like a spoiled little brat. He wanted to still your thunder because you were doing your garden boxes and he didn't want you to have any pleasure in doing them, so in his PA way, he wanted to make you angry. I'm glad you remained calm about it.
As for the keys, he's just picking at you. He knows good and well that you always have a house key on a different ring. Again, he doesn't like to see you enjoying yourself and he wanted to annoy you so that you wouldn't have fun.
You might want to check to see what he's tossed out...it might be something you can use. Of course, he's not going to comment on you going out...he's PA and he'll find another way to get back at you! LOL!
You are doing great...keep up the good work and whatever you do, don't let him see you sweat!
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.