Age ranges on toy boxes are usually a good guide. Noise making shape sorters are cool. It's OK to pick toys you would like to play with too. The swim vest system with little foam slabs that you remove one at a time really works. Day care, after school programs, summer camp, etc.
Modern lice are immune.
Mechanical removal is your best bet. You will need a good lice comb. The one made by NPA is particularly good. Buy one before you need it. You can buy cheap reading glasses at a drug store that work as a magnifying glass, keeping both hands free while you comb.