Sorry for the delay.
1 There is no way of doing that. People can make false allegations of claims and regularly do. All you can do is deal with it afterwards.
2 No. In fact, it is their problem rather than yours. All you have to do is notify.
3 Yes, you could lose your no claims bonus. They will not raise the premium per se but you will lose the reduction.
4 There is no way of doing that. If there is a claim then your bonus would be affected. I suppose the only thing you could do is consider a claim against them if you do lose your no claims bonus.
Can I clarify anything for you?