1000 points is about three or four squads plus some support (HMG team or mortar, sniper). Standard size would be either 1500 or 2000. So add a couple of tanks, or some half tracks and an extra squad, etc etc, and you'll fairly quickly hit 1500.
The GEG sets are a great starting point, and then you add additional stuff ie another squad and a tank or two.
Model count depends on the list. Russian or British infantry will outnumber SS, but you are looking at between 40-70 models depending on the army, how many tanks, etc.