Do what you need to do with the pictures! If the reminders bother you, then by all means take them down and put them in a box.
Lovehub has other good ways to deal with the calls.....Be positive but firm.
I say hold onto the car for now....Just park it in the garage. I do agree with not sending it to her....
I want you to understand that there are really two things going on for you now. You are just starting the long voyage of DB'ing your marriage. That is a fruitful voyage!!! There is also the business side of all this.
On the business side....It sounds like you pay for everything for her, right down to buying her a car. There is also the outstanding $100K loan to your FIL. I suggest you consult a lawyer...This doesn't mean you are filing divorce papers, just know your rights as a husband and father. You do need to protect yourself....and at the same time I do feel that you paying for everything your wife does in light of the current situation is asking a lot. Before you do anything though...talk to a lawyer.
I like the dinner out alone idea....sounds like a good plan. Keep it alone....no women, but maybe a guy friend. If you want to Db your marriage there is no room at all for dating, etc....so don't even start thinking it.