Windows 7 is technically supported, but gets the least of our test resources as its not under active development from Microsoft (and hasn't been since 2015). The security patches run out January next year.
Similarly, the overwhelming majority of users are running 64-bit systems. Cakewalk will still run most 32-bit plugins via Bit Bridge (or J Bridge).
I'm not sure where "Cakewalk on a rental basis" is coming from... We've been delivering a free version of what was previously SONAR Platinum with all its core features intact, and improving upon that for almost a year. Once the application has authorized on your system, it's not going anywhere.