Paddle from Greenfield MA to Middletown CT

My friend and I are aspiring to paddle from Greenfield MA to Middletown CT this year. Neither one of us has much past experience to draw from. We will likely split the trip into a couple separate sections, each section paddling two days with a night of camping in between. A few questions we are pondering as we prepare:

1. What are the main considerations when choosing between a canoe or two kayaks?
2. In general, what are the seasonal differences in the flow of the river?
3. How much does preceding rainfall effect the flow of the river?

Questions 2 & 3 are regarding whether it's necessary to take cautions if the flow is too fast, but also how to time the trip so that the river is not at its slowest.

Thanks. We'd greatly appreciate any tips from those familiar with this beautiful river!

-jon

With a MA to CT paddle in mind, consider starting just below the dam in Holyoke to avoid a long portage. There is camping available but the choices are limited on that stretch of the river to Kings Island. Starting from Holyoke, we made Middletown on the second day.
Can't speak to variations over time, but we saw an average of 1 mph of current. USGS has some river flow meters, but they report in height or volumetric flow rate which can only loosely be correlated to water surface velocity. I would be more worried about river flow further north, the river is wider and slower in the stretch you mention.
I will put in a plug for the river further north. Remote campsites are available and the wildlife is more plentiful. Worth a bit longer drive. At Kings Island we listened to the traffic on I-91 all night but at least we didn't have a problem with a smell from the sewage treatment plant on the western shore.
Best of luck and enjoy your paddle!

Thanks for the advice!
We hope to do the whole river one day, but we will likely start with the Greenfield to Middletown section for symbolic reasons, as we hiked between those locations over a previous year :)

So there are no challenging rapids between Greenfield and Middletown?

What time of year was your trip that you're referring to?