Yes, you should be able to save costs by stripping all the components, everything including the BB guide, but I wouldn't worry about stripping the paint. Powdercoaters have a tank of solvent that they dunk the frame in. Everything is dissolved (including decals) and leave the frame prepped for coating. Very low labor effort for this and if the frame was powdercoated before, I don't think you can remove it without solvent due to the bonding process (unlike paint). In the old days, they used sandblasting but I don't know if anyone does that anylonger.
Be sure you find out who is to obtain replacement decals - you or the powdercoater. Some places will reproduce decals if they are no longer available (maybe CyclArt?).
Ask about colors. Some colors can be done in one coat while others may take two. If you want a clear coat to make the finish super glossy, ask about having the decals applied before the clear coat. Each coat and each color adds to the cost. Powdercoating doesn't allow you fancy designs as powdercoating must be done by masking areas rather than freehand painting. Each layer of powdercoat is also more vulnerable to chips. The thinner you keep the coats, the more durable.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.