1. Does he have to pay me to remove my name from the deeds?
No, he has not to pay you if you agree
But there are some taxes to ba paid legally for you and he could pay on your name
2. If he refuses to sell, does he have to pay me?
If he sell or not, if he wants to erease your name from deesds he will need your sign
3. I paid nothing towards the house and no running costs, so does that give me any rights at all?
Yes, you are legally the owner of the 50 per cent of it Its not matter who pays now, you should pay 50 per cent of taxes and expenses
4. If I refuse to take my name off the deeds, will this still be the same problem for my children in years to come when both of us have died? If you refuse to do something the main problem is for him really
In no case your sons problem
The real thing now is what do you want, if you want money or not. Because he will have to accept your decision