(BTW, Lucy, the F2 does indeed have on board mixing.)
Ah, I thought so. In which case, I don't think you'd need any mixing?

Running 2 wheel drive at the back not sure what to put on the front to allow it to run smoothly.
I'd put HDPE blocks or static wheels like I do on my Middleweight to allow it to run smoothly. I can show how both are attached if you want. At this stage, it has FW stage parts so I'd aim for that.