Welcome to TB and bassdom.
Keep in mind, many geetar pedals work great with bass. Almost any Way Huge does, and their Russian Pickle is a nice fuzz box.
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Bassic Gear Review One of the best pedal reviewers, and gives you a good idea what pedals work for bass. Beware, Will makes everything sound good! You can also search the effects forum here to get ideas.
Get out to your local Guitar Center, Sam Ash, etc. and try out some amps there. Try before you buy if you can. BYOA, Bring Your Own Ax.
Wattage matching can be important with a bass rig, giving a combo a bit of an edge for a new fella. That being said, I would suggest separates, so you can add or upgrade speakers cabs when you need to get louder. Post here before you buy. If you get an amp that is 2 ohm stable and has a 2 ohm switch on the back, like a Mesa D800/D800+, you can "detune" it by setting it to 2 ohms and using an 8 ohm cab. "Detune" = reduce the wattage output. An HPF can help save your speakers too.
Frequency response, if you look at that, don't worry about reaching down to you lowest open string. Unless you drop tune, you don't need to go below about 50 Hz for a 5 string low B, or 70 Hz for a 4 string. The first harmonic is the loudest, and those two frequencies I listed are about 10 Hz under the first harmonic. Forget the fundamental frequency.
Go light! It takes time to build up the muscle mass of a bassist to lift the heavy cabs



Used gear can be a bargain. If you change your mind, it can be resold with less of a loss if any. Older heavier stuff is dirt cheap and works. Maybe you can build your bass muscles before you have to move it for rehearsal

I would avoid used gear that is not serviceable unless you get it at a disposable price. Genz Benz gear is probably the best of the older gear as far as tooby goodness from a class D or AB amp, and most or all of it is factory level serviceable at a flat rate (some of the really old stuff might be parts and labor). My favorite:
Genz Benz Streamliner, Part 10 | Page 53 | TalkBass.com
Bargains are always there, so again, post before buying.