[Imp]

Its a game designed to let you cover all aspects, points price is a reflection on unit capability, rarity is not taken into account.
Its up to you to select a force which can be realistic or otherwise. Either decide for yourself or use a system you like.
Example roll a couple of dice if you want to upgrade to a Sturer Emil can if roll a 2 thats about a 3% chance you get it.

Equipment choice is upto you can upgrade straightaway in a campaign or delay it till a time you feel is right.
Playing Germany there is a desire at least for me to play with all the toys but you dont have to upgrade to Panthers for example. Could just stick with the Mklll's & say upgrade one to a Tiger.

You can simulate unreliable stuff easily enough as well apart from the fact they will still retreat, played not long ago as Germans at the end of the war criticaly short on fuel.
Just rolled 2 dice each time they moved. If rolled lower than the number of hexes they moved or doubles fuel is ctitical. Then roled 1 dice for in each hex entered 1 out of fuel 2 now runs out on a 1or 2.
Could just roll say 11+ for breakdowns each hex entered.