From my experience basses do work slightly different than guitars tonally with a boost. For instance my brother has a BBE sonic stomp in his bass rig (he uses a ss ampeg) and when he turns that thing on his bass sounds monstrous. I tried using his sonic stomp once when I had my ss amp and all it did was make it sound muddy. He’s tried my using my lpb-1 a few times and it does make it a little punchier and makes his low end boom a little more (not nearly as much as the sonic stomp though). As for the things like an auto wah or envelop filters, it most certainly gives it a different effect. Overdrives and distortions will do the same thing. I have a q tron and I have to be careful when I have my Tube Screamer or LPB-1 on otherwise it icepicks super easy (I have both in front of my q tron).

As for buying a tube amp. I originally thought people were crazy for spending ridiculous amounts of money on tube amps. Once I got one (I have a Bogner Alchemist) there is no way I could or would ever go back to a solid state. I would definitely have a tube amp on the top of your musical list as of right now. I got mine off of craigslist for pretty cheap, so I would recommend starting there.