Painting fenders, opinions, advice

Got some of Grant's lil fenders, and think I going to attempt paint myself(thinking spray can). There are some cracks(?) in the gel coat. Based on advice from a supposed expert coworker, I am thinking scuff the gel coat, high build primer, block sand, another coat of primer, block sand, repeat as necessary until fenders are smooth, then color coat, scuff, another color coat. Does this sound right? Also there are a few spots that could use some body filler, at what point do I do the filler? I am planning on spray can bed liner or undercoat on the undersides. What grit sandpaper do I use at which points?
Fender

Close up showing cracks

Thanks
Aaron
Fender

Close up showing cracks

Thanks
Aaron