First of all, let me welcome you to the forums and to the dark side!
I'll tell you how I do my builds, and I'm sure that you will receive more info on your questions as the day goes on.
1-After building I give the model a good wash with liquid dishwashing soap and then let it air dry.
2-I do not use primer unless I've had to do a lot a flling and sanding, which on your Sherman you should not of had to do (hopefully).
3-Apply the base color.
4-Apply decals. I set mine with Micro-Sol. I do not use Future as I've never had any trouble with decals not setting properly. Lucky I guess.
5-Apply wash to the entire model. I use thinned enamel or pastels (chalk, NOT oil) thinned with water. Remove excess with mineral spirits (for enamel or water for pastels).
6-Drybrush with a lighter shade of the base color to bring out the highlights.
7-Weather with pastels or paint. If weathering with pastels, you will want to apply them heavier than usual so when you apply a dullcote, the pastels won't all blow away.
8- I finish with a coat of dullcote.
I use enamels as you can tell. With you using acrylics, everything is about the same.
Hope this helps...good luck, and lets see some pics when you are done.