Mike,
Benefit of not stripping: saves time as long as the paint is good (no chips, runs, etc.). Yes, i would sand off the stripe.
Inasmuch as this is your first project of this sort, i'd use Scalecoat II in a rattle can, practicing a little bit beforehand on a scrap of plastic to get a feel for the spray pattern, ideal distance to put on a light coat. You don't thin the stuff in a rattle can; if you go the Preval route, you will need to use Scalecoat II thinner (i generally use inaccurately measured 10%-20% thinner).
After it thoroughly dries i'd use some rattle can Testor's Glosscote in the areas i'm going to be putting decals.
Sealing the masking tape: For example -- if you were to paint an area - say a white stripe. OK paint it on the primer, now your planning on a dark color next to it. Mask the stripe, burnish the tape, and then spray a light coat of Dullcote on the edge of the tape to further seal it preventing any of the dark color seeping (bleeding) under the tape onto the white. This is just an example.
Decaling: follow the instructions on the bottles of MicroSol and MicroSet applying decals to the areas you have lightly sprayed with Glosscote. After all is done spray the whole model with Dullcote.
Advice -- Take your time!!
jackson
