Depends on the company. Some will see it from the POV that you have a false sense of security and that you would therefore more likely to drive beyond your capabilities. The others will see it as improved stopping distance, etc. The premium increase will again, depend on your individual circumstances and the company.
these are qu's that can only be answered by your insurer! speculation on this and that is pointless as what one person gets from even the same insurer doesnt mean yuo will unless your in the same postcode,age,sex,job,car etc..........
It may do. Then again it may not. As custard said, it is impossible for anyone on here to give an answer other than 'maybe'. There's too many variables involved to give a meaningful answer.