1. yes.
2. basing is entirely up to you. You're moving sections and fireteams and weapons teams, but how they're based doesn't matter. Single basing makes it easier to remove casualties, but multi-bases can be used with some method of tracking casualties. My armies are based in a rather FoW-ish manner, but some players use single figures.
3. 2 platoons plus a few supports is a good start. Most games are about a company per side. (so approx. 60-120 figures)
4. Sure. The weapons are pretty much the same.