GC28101 Pro Flex Rv Flexible White

Can this be used to seal roof skylight on rubber roof?

How many windows will one tube seal? Or to put another way, how many total inches of area will it cover?

It appears the seams on my trailer have previously been sealed with silicone. Can I use this product over silicone?

Suitable for hairline cracks in roof of 2001 coleman fleetwood popup? i believe it is abs not epdm roof.