for the backend yes
frontend is a separate project but its using similar things to construct it so if its a vital feature it can be redone in lemmy-ui pretty quickly. Already gave them code block support for 0.18
Yeah you can redirect or you can make lemmy.[something] and forum.[something] point towards the same ip or same port depending on how youve set it up (if you want lemmy.[something] to still work else you can just change it to forum)