Just some random comments:
The road from St. Mary's to Waterton is very curvy and can be a rather steep grade. The road is narrow too, so be prepared for drivers who are looking at the scenery more than at the road itself. The border crossing at Hwy 6 (which is the one closest to Waterton) is very small and I've never had much of a wait there.
If you are staying in Waterton, the Bear's Hump provides a nice, but very steep, hike up a hillside right by the Parks Canada visitor centre, where you can see all of the townsite and back into Montana. The Red Rock Canyon drive provides the best wildlife opportunities--everytime I've been, I've seen at least one bear near the roadside. Not sure it is really safe for a bicycle. Food offerings are a little pricey in Waterton (there is a small grocery-type store in town, but even it has some pricey offerings). There is a camp ground right in the townsite very close to the lake. As I recall, due to wildlife hazards, that is the only campsite that does not require hard-sided campers and allows tent camping (but don't quote me on that).
Waterton and the surrounding area can be (and often is) very windy. Until you get to Canmore, the winds can be very rough as they come off the mountains. Summer isn't exactly windy season, but you never know.
It sounds like you are planning to go up Hwy 22 and over on Hwy 40. Consider stopping in Longview at the Longview Jerky Shop, if that type of food appeals to you. I personally think that the press that they get is better than their food. The scenery on 22 and 40 is among the best in Southern Alberta, in my view.
If you are so inclined, the McDonalds in Canmore (it is very near the hospital and the visitor information centre, near the last exit into town off of the TransCanada highway) may have the best views that I've ever seen from a McDonalds.
Once you enter the entrance gate into Banff Park, there is a very good bike pathway that is adjacent to, but not right up against, the highway. It pretty much takes you all the way into Banff (the town). From there, I don't know about the availability or route of the bike paths. [ETA: Banff townsite, in my view, is not worth a stop, but there are plenty of camping, lodging, and food choices and I'm sure that there is at least one grocery store there (although grocery prices would undoubtedly be cheaper in Canmore). Banff is a mountain town that is wholly indistinguishable from any other random shopping town. I'm sure it was lovely 30 years ago; today it isn't. The crowds in July may be overwhelming.]
You might as well stop by Lake Louise (and its nearby cousin, Moraine Lake), but to see Lake Louise requires going up a very steep road. I don't like driving up it; biking up it would give me a coronary in no time. Moraine Lake is overwhelmed with visitors, particularly on weekends, and parking can be very hard to find. Biking would likely be easier, but again, watch out for drivers who are looking more at the scenery than at anything else. (As a complete aside, I fully endorse a night's stay at Chateau Lake Louise, but only on the gold floor; the rest of the hotel isn't particularly worth the money; food at the Chateau is pricey, staying on the gold floor gets you a substantial breakfast and evening canapes that can substitute for dinner). [ETA: (1) If the Chateau isn't your thing, there is a charming hostel in the Lake Louise townsite--I think that it is a YHA---and an adjacent restaurant (Bill Peytos' Cafe) that I find to be a decent value. There may be a small grocery store in the Samson Mall (not really a mall, more like a strip centre, and it is in the parking lot where the Parks Canada visitor centre is located); (2) If you wish to see Lake Louise, see it before 10:00 when all of the day trippers come to visit; (3) If you visit Lake Louise, you might want to consider doing a teahouse trek as well. I personally think that the Lake Agnes teahouse is superior to the Plain of Six Glaciers teahouse, but to each their own (both offer somewhat meager food options and lots of tea choices, but bring cash and expect prices to be a little high for what you get). Either way, the hike is not difficult (particularly not for someone who is in the kind of shape that I'd expect you are in), and once you get to the teahouse, the views are hard to beat (Plain of Six Glaciers gets you pretty close to Victoria Glacier, which is the glacier at the end of Lake Louise; Lake Agnes gets you up looking down at the Chateau, next to another lake (Lake Agnes), and in a bit of a 3-sided mountain bowl). From Lake Agnes, you can continue upwards to the Big Beehive or the Little Beehive; the latter gets you a majestic view looking back and over the TransCanada highway, a railroad, and other mountains, the former gets you a view looking down over Lake Louise.*]
There is a Parks Canada visitor centre just off the TransCanada highway going towards the Lake Louise townsite (such as it is). It is worth a visit for the maps and information on animal sightings.
Going up the icefields parkway to Jasper, the best scenery (in my view) is from Lake Louise to the Athabasca Glacier. Lots of side stops on the way up there (Peyto Lake, for starters...). There is, as I recall, another Parks Canada visitor centre in the hotel/restaurant/museum across from the Athabasca Glacier. Once you pass the Glacier, however, the scenery becomes "more of the same" and, frankly, I just wanted to get to Jasper.
In Jasper, a decent little eatery is the Bear's Paw Bakery and its companion, The Other Paw. Jasper is a lot less crowded than Banff, but the main street offers the same kitsch.
* In case it isn't clear, Lake Louise is perhaps my favorite place in Alberta, and probably one of my top 3 places in the world.