Resin and vinyl are different. Vinyl, besides staining like there is no tomorrow, has more tooth (texture) than resin does and grabs color faster. Resin, particularly if its been well sanded, is much smoother a surface and pastels tend to glide over it more than sit in place. I recommend finding a cheap head - perhaps a damaged one - and using that to practice.
When painting vinyl or resin you can use any water based acrylic paint. The only difference between "artists grade" and other levels of acrylic is the amount of pigment in the paint and the lightfastness. Unless you are planning to sell your products on the market it really doesn't matter what brand you use. If you are planning on selling your faceup skills then you need to use artists grade paints - the buyer expects it.
In terms of pastels technically any CHALK pastels will work, but like all things there are a variety of types and qualities. Like paint pastels vary in the amount of pigment in them. The cheaper harder pastels contain less pigment, more binder. Being as I do fine art with pastels as well as dolls I only work with high grade pastels: Windsor & Newton, Sennelier, that level stuff. You have to go to art stores for them, you can't get'm at Walmart. For hobbiests Rembrandt is a decent enough brand - not the softest in the world, but quite serviceable and affordably priced in sets. Again though, if you are planning on selling your product use the best you can afford - your buyer expects quality for their money.
And finally - you can refer to this valuable list started by Itsaiya and stickied at the top of the Tips and Tricks forum:
http://www.dolliehsanctuary.com/sanctuary/viewtopic.php?f=13&t=25 It's all about recommended matierals.