Hey there, sorry for the delay, had to get situated again after our trip to Wisconsin 🙂
A table 3 feet across should see you just fine and for Napoleonics you can probably play on even smaller than that.
Infantry move 3-6″ depending on deployment mode.
Fire ranges are 6″ for muskets and up to 16″ for the end of period (FPW to WW1).
Typical game should be around 10 units so figure 40ish stands, but you can of course start smaller.
Hope that helps!
What periods are you looking to use it for?
Nordic Weasel Games