Shame about the dust problem Evan. Give it a light rub-over a few times with tissue - if the dust is just in the clear coat, it should remove it. If it doesn't, then very carefully rub over with very fine, worn out wet n' dry, used wet. Dry off, inspect, lightly polish off, and re clear coat if required.
Matt and gloss varnishes can be mixed, although it will take some testing to achieve the desired amount of sheen. Also, with varnishes, particularly enamels, the viscosity will increase, therefore giving a 'thicker' coating.
I 'binned' normal clear coats a few years ago, apart from the odd gloss finishing coat, and now use Future mixed with Tamiya Flat Base, to produce anything from dead matt, through semi-matt, semi-gloss and so on.
It only needs a small amount of the Flat Base, mixed with the equivalent of a cap-full of Future, and again, trial and error will provide the desired result. Test on a piece of scrap - it only takes around 15 minutes, maybe 30 minutes at most, for the 'mix' to be dry enough to asses the finish.
Note though, the Flat Base will need thorough stirring before adding to the Future, and will need to be stirred again to thoroughly mix in with the Future. Once you've found a 'mix' you're happy with, you can then prepare bottles of the various 'sheens' for use when needed. I use the empty Tamiya paint jars for storage, labelled accordingly.
Just thought though, can you get Future where you are? If so, it saves a heck of a lot of money on small, expensive bottles of different varnishes, and a bottle of Future literally lasts years. Gives a great finish too!