According to Trek specs it is a 13-34 Sunrace freewheel, but Sunrace “used” to make a 13-30 7 speed freewheel. The 13-30 was a very nice range in a not so nice package as Sunrace freewheels don’t hold up very well.

You can use a standard Shimano freewheel tool, Park Tool FR1.3.

Any Shimano compatible, you can use a Sunrace, 7 speed freewheel will work, but you will have to choose between a 28t and 34t max cog.

John