I put 9 figures on each base, or 4 for skirmishers. Some people might prefer a denser look, maybe 12 figures. For the rules I'm using these armies for, the number of figures on the base doesn't matter.
I use wire spears (I sell them, as do North Star and others), but I've also seen plastic brush bristles, pins, and flower-arranging wire used. They all work well!
I don't know if anyone uses sabot basing for these smaller scale figures. Certainly they do for 28mm figures, so you could do the same, just scaled down?