Everyone has a game idea they want to make. Unless it was a game idea I was passionate about (I'd helped conceive the game's mechanics), I won't work for you without pay. Right now, I like to do smaller contract jobs on the side (Imagine writing a program to do something specific for someone, and getting payed when I finish it). It'd probably be better, if you're going to pay people, to pay them by program / mechanic, than by hour. Since your indie, paying someone by hour won't work at all. There isn't an office, and there's no way to keep track of how much they worked.
For your portfolio: Use GameMaker. If you're an artist, employers will far rather see a smaller game made with a tool that represents your art, rather than some hard-coded game. They're looking for an artist, not a programmer. I can guarantee you that if I was hiring an artist, and one came to me with a portfolio of good sketches / 3D Models, and the other came to me with 1-3 Games made in GameMaker with good art in them, I'll pick the latter.
For an artist, I'd look for:
- An understanding of sprite-sheet creation
- An understanding of basic Art Logic / Drawing
- Good 3D "visualizing" skills
- A game they'd made using their art.