Normie1, don't use Testors flat finish. It models on the finish. It will leave your model looking like it needs a dermatologist. My recoommendation is to use Microscale flat finishes. I've never had a problem with it. I've also used Floquil with great success. I'm saying this hoping that you have an airbrush.
If not.... I'm not sure what your best option is. Perhaps somebody could help here.
That said, somebody put out a post that I want to try. They used Tamiya flat base mixed less than 50/50 with Future. I think I would start with something like 25% at first and experiment from there. Future can go on by airbrush, brush, or dipping. I'm not sure how this mixture will behave, but I want to give it a try sometime soon.
As far as clear acrylic gloss goes there is only one choice and that is Future Floor Wax. It will never yellow. Great stuff and easy to use.
Hope that helps.
Good luck/Dave