I have 2 different projects in mind but I need a bit of help with getting the right color and texture. I have only used metallic colors before (Mehron paint) so need advice on what paint would work for this instead. Both would be for full body, face, and hair coverage.

One idea is to make the model look like a marble statue. the second is to make someone look similar to the statue of liberty -  the greenish color that copper turns to. what paint would I use to get such looks? what would be best to apply the paint? I have been using sponge brushes for the metallic paint projects I've done in the past.

Any help is greatly appreciated!

Both projects can be accomplished by hand painting.
I'd layer airbrush and hand painting

Stone:
Matte body paint of your preference.
Hydro-sponge a base of the dominant color.
Sea Sponge highlights and lowlight colors (for texture and visual interest)
Hand paint cracks using a feather or script brush.

Just be mindful of body mapping - try to flow color WITH the body planes instead of counter or the end result can look choppy.

Statue of Liberty.
Metallic copper base wit metallic highlights and matte shadows.
Hand apply green patina by brush or even a drip bottle if you really want to have fun with the patina.

What brands to use is a matter of personal preference.
Something like Mehron Paradise will be matte and blend well.
Something like WolfeFX will be matte/slight shine and is ideal for crisp lines.

Another painter may come on and say I'm upside down and backwards.
Just like with any bodypaint, there's more than one way to reach the same end.