Planning to have concrete poured into a new section of basement (part of home addition). The area is roughly 16' x 20', concrete will be poured through a basement window which is about 16" x 24". Right now I have about 4" of stone down, planning to put plastic over the stone and then wire mesh elevated to sit at the center of a 4" pour. I've done smaller concrete projects before, but wanted to make sure I was clear on a few things before deciding if this was something I should try to tackle myself.

1) Do I need expansion joint material at the edges of the floor? Walls are block.
2) Do I need a relief cut anywhere for a floor this size?
3) How do I go about screeding when dealing with a wall-to-wall pour? When I've done concrete before there were always wooden forms in place so leveling was easy.
4) If I have the wire mesh elevated to sit in the center of the pour, will I be able to walk on it to do the screeding, etc. Without bending it all up?

A few other things to mention - this will basically be just a storage area so I'm not really concerned with how 'pretty' it turns out. Also not sure how much I need to worry about it being perfectly level and flat, I've never had water issues in this basement.

Might also think about putting in some piping for radon, just so it's there in the future in case I ever have a system added. I may post that as a separate question though.

Thanks in advance for any help