I'm actually planning for a trip to Kamakura around Aug time after alighting from the plane in the morning. I'll be putting my luggages at hotel first @ Ikebukuro before setting off to Shinjuku to get the Odakyu pass for Kamakura.
I've seen a round course for Kamakura on a website and wonder if it's feasible for me to follow.
http://kanagawa-kankou.or.jp/english/modelcourse/kamaku...
I'm looking at the Day 2 course.
estimated time of leaving Ikebukuro is either 1025 or 1125...

As far as time goes, that course looks doable. The temples do have closing times, they vary from temple to temple. The final temple on your itinerary (Hasedera) closes at 5:30 pm, and if you follow the walking course suggested touring times for each site, you should be there before then. However, keep in mind, the time you will spend waiting for the bus is not factored in.

The two biggest problems with this course are:

A) August is hot. Really, really hot. And humid. That course requires a lot of walking, not only walking from temple to temple, but also walking around the temple grounds. It might be really uncomfortable.

B) Generally, the Day 2 course looks like a more interesting collection of places than the Day 1 course, however, it leaves out Kenchoji Temples, which is really worth seeing. It covers a big area and there's loads to see.