Mojave and High Sierra support 32 bit applications.
Catalina does not support anything 32 bit - no Applications, Extensions or Drivers and there is no work around - period.
Support - Catalina may still get some Security updates, the other are basically end of life
A SSD of at least 256 GB or larger is doable - less going to be an issue
RAM is good thought more is better.
Features - Catalina has more but depends if one has other Apple Devices in the stable that need to work well with Catalina. Also, in Catalina iTunes is now split into 3 separate Applications. Podcasts, Music and TV plus Books