Start with LC White Pad with Optimum Polish
and finish with LC Blue Pad with FS UPP
if this isn't enough then -->

LC Orange Pad with (Optimum Polish)*
Followed by LC White Pad with Optimum Polish
LC Blue Pad with FS UPP

*Does Optimum Polish work well with an orange pad or do I need Optimum Compound to use with an Orange pad.

Also is a Grey pad better than a Blue pad for sealants?

 

Depends on the results attained with your above procedures!
Both pads will support OP. Orange supports OC better then white though, and you would attain more favorable results IMO. OP and white finishes out VERY nicely.
As for your sealant pad, blue or grey will work fine. Red is even gentler.