These are to do with a game

How would you say the following sentences please?

1 You can upgrade 2 levels per/on a level town hall. You can go from level 8 to level 10 cannon on a level 8 town hall.
2 With the troops I have/with my troops I can easily...

You need to get at least one star to advance to the next level, how would you say:

3 I have 3 stars on/at/in level 40.

Is it correct to use 'when it comes to'?
4 These soldiers are useful when it comes to blowing up walls. They sacrifice themselves.

Thank you