your adhesion should be ok with your current process. I always try to do some sort of mechanical adhesion prep as opposed to just the chemical. 200 might be a bit to agressive a profile, so stick with the 400 for now. Once you get your sandblaster, you can skip that one alltogether. As for the lab-metal, make sure it is dry and fully set before powder coating. Just remember that this stuff is very tough to sand, so don't go putting a big glob of it down hoping to take it down like you would bondo. Other than that... I don't see any major issues flying your way. Have fun and of course.... we wanna see some pictures of finished parts
