The two different tins of FK1000P I've had were very different; the second/latest one was a lot less dry and a lot easier to work but it was still a "hard wax". Yeah, you can use FK425 to ease things along and I've even dampened the applicator with FK425 and it worked fine (didn't compromise durability the way I thought it might).
Yeah, the FK1000P residue can be a bit of a hassle, so be sure you buff it all off (heh heh, in other words, do it right

). Be careful around things like PPF edges and badging, and be sure to W-O-W-O if you try using it on trim (works for me, but "don't try this at home, kids!").
On the FK1000P vs. OptiCoat comparison, I've gone from FK1000P x many to OptiCoat on the Tahoe's wheels. No comparison at all after the first few months, the coating has stayed just like new well past the point where the FK1000P would start to drop off. FK1000P might be my choice for the best thing this side of OptiCoat, but that's as far as I can go.