Okay i'm terrible at makeup and i'm new to it is this greasy at all does it run? do i need setting spray i need help jesus

Not greasy, and no, you shouldn't need "setting spray" unless you perspire alot. As makeup goes, it's very inexpensive. I like the packaging... once you've used up most of it, you can "dip" the pump and apply it to a sponge to get more of it out of the bottle.

Is porcelain good for light skin with red undertones?

I have light skin and I'm VERY pink and this is a perfect color match for me.

Is this oil free or not?

Yes, says on the back above the directions, OIL FREE / SPF 15 SUNSCREEN. (Referring to the e.l.f. Sand #83112)

There’s no option to change the shade. What shade is this?

This shade is natural. Or in likeness to other colors nude.. I bought this color and it was too light so I returned it (or rather a refund w/o return)and got a darker color.. what I did to find the darker color was find out the names of their colors then typed it in the search bar under that name ..ex: elf flawless finish foundation, buff. And that’s how to get lighter or darker colors. I now mix the 2 and works great