New to MTG Arena, need general help!

Hey everyone! So I’m new to MTG Arena (I have completed the tutorial) and wanting to play Pioneer decks, I have kinda a lot of questions about it all:

When I go to make a deck, I don’t see the option of Pioneer, should I just click Explorer and make Pioneer off that because I have heard they are the same?

How do I start building a deck? Do I just go to the shop and spend gold coins on packs or is there a straight way to do it?

I’m really interested in Orks, Vampires, Demons and that sort of stuff, is it possible to name the deck based on that topic?

Thank you!!