Hi Lang, also this part of your question here:

> As I've booled/unified it and there aren't any curves I can't rebuild it just in case this is what I should've done?

There isn't anything actually wrong with what you have done so far - if you want the fillet to be automatically made to be smaller you could do that by building a solid first with capped ends and then filleting that. But it's not like there is anything particularly wrong with the fillet you are showing there, if it's too big for what you want then you can just cut it using Trim...

- Michael