There arent winter clothes in the game, no. They are included in the infantry equipment which includes everything a soilder needs. As for the lenght of the campaign you assing frontlines and offensive lines, which your troops then will advance to, but not any further. You can actually create multi-phase battleplans which you can execute in steps as far as i know.
As for the myth about the german lack of winter clothes, thats simply not true. The reason why germany lacked winter clothes etc at the front wasnt because they didnt prepare, it was because the supply channels were that narrow that they were forced to make decisions between clothing, replacement equipment, ammunition, fuel etc. It was simply very hard to supply the troops at the front and the gasoline engines tended to freeze if they werent running constantly because of the very cold weather, which drove up the fuel consumption alot.
People dont seem to realize that quiet an big chunk of the logistics in WW2 was done by horse and wasnt 100% motorized. Germany never expected to win the war before the winter started, that was was an quote from WW1, where all involved nations expected an 4 to 6 months war.