Sorry in advance for all the questons..

I've just started to learn screen printing and am using regular acrylic paint (liquitex) with a screen printing medium. I've noticed I get a lot more blending of colors than I expected - which is cool but sometimes I don't want it. I'm sure I've seen printing of lights on darks that don't blend at all. Or am I wrong?
I tried using pure acrylic and still got quite a bit of mixing between then colours. I've read people use a base coat, but I wasn't sure what. Can somebody recommend a product?The paper I'm printing on is pretty cheap just for testing, maybe 150gsm, I assume this is also a factor. Also forgot that the acrylic would dry really fast and now is stuck in the screen. Any tips for washing it out?

I'm living in a shared space at the moment with no room for burning screens, so I've just started out making hand cut stencils. Any recommendations for getting a good result? It's worked pretty well so far. I'm using regular printing paper for the stencils. Anyone tried a thinner paper? One issue is a slight darkening of the very edges from buildup of ink because of the height of the paper.

Any advice on anything would be great, thanks!