Welcome aboard.
I noticed the bit on your blog about the 4 year old.
We run a school club and would recomend starting him off with PBI from Peter Pig(fair enough our youngest player so far was a 10 year old, but we have to cope with 10 or 20 players at a time).
It's played on a squared board, so no problems/arguments with measuring, and no arguments about cover, if there is cover in the square your figures are in it.
It uses "stands" of figures, but you can use any basing style so long as you can recognise if a stand is a command stand, an mg stand, or just a rifle stand. Or you can use single based figures.
There is a slimmed down free starter version :
http://www.peterpig.co.uk/PBIQS.pdf