Unfortunately it appears all of the most popular (and feature-complete) Vim-style plugins for Firefox are dying with the upcoming Firefox update dropping support for XPCOM/XUL plugins.
I still use my old second-hand Samsung N220 Plus occasionally when I'm travelling, as it's lighter than my main laptop and I can't afford a light + performant one.
I'd never actually considered whether to run 32-bit or 64-bit OS on it, and just installed the 64-bit by habit.