Good answer!

+1 on the tack cloth after you do the MS wipedown. They only cost a couple bucks.

Re: your planned 50/50 MS mix - that might be a little too thin. I used around 35%, give or take, but it also depends on temperature and humidity, so its not the same ratio for everyone every time.

Remember you are going for a consistency like low-fat milk.

Here's a pic of what a first coat should look like when its done (this is rustoleum gloss black) - notice that there's hardly any coverage at all. The second coat didn't look much better. As Charger said, you won't even start to get coverage until the 3rd cost.

Also - you really want to squish out most of the paint off the roller by rolling it in the tray before you start to apply it to the car. Thin, Thin, Thin.....