X2 but stay away from the 3.25 a foot guys... you will get what you pay for...
PREP, PREP ,PREP
Grind, shotblast but don't etch last thing you want to do is introduce moisture to your slab before coating.
Cracks can be patched with epoxy paste and hold up very well. If there is movement in the slab as weight gets transferred from one side to the other, they may start to re appear.
Also you need to prime the floor with a lower solid content epoxy, 100% will not penetrate for a good bond and will produce a lot of little bubbles. Pennywise and I use the same manufacturer and have had good with luck with there quality and consistency.
They sell direct and ship if you decide to take it on your self.
Good luck reach out to me or Pennywise if you have any questions.