The park is open year round. There is at least 1 hotel that is also open year round. Although Northern Lights can be seen from Waterton, like you suggested it is better to go later in the year. Keep in mind that certain areas of the park become closed to the public after snow starts to stick to the ground.

No matter which way you go is beautiful. But the most scenic is from Pincher Creek to Waterton. My family does this route both there and back every year and enjoy it every time. Don't rush, there is so much to see. Enjoy our local treasure.

Am not sure abt the group camps but there were camps

The Lakes in Waterton are the Upper, Lower and Middle Waterton Lakes, as well as Cameron Lake

Absolutely

It is not tent per site, it is person per site which is 6 per site. We were there just last week and we got 2 sites but we all came together close to each other in the middle of two sites. We had 5 tents altogether.

Camp

As Ace said, most businesses are from May to October such as where I work. Though some start in June, and many close by September.

Fishing licence required