I recently got a Boss GT-1 Guitar effects processor and my question is should I use it in the FX loop or is in the front of an amp fine. My other question is if my effects processor also has an amp modeling function, is getting an amp with a good preamp even worth it, if the FX loop would bypass it? (P.S sorry if I have said any thing dumb or wrong I'm new at this) side note what affordable amps work well with a Boss GT-1?
No, definitely not as a rule, but it's something to try. The best thing is to try both and use what sounds best to you.
It depends on the type of effects that you are using and to some degree personal taste whether it will sound better in the FX loop. Most people tend to want volume based effects like distortion/overdrive in front of the preamp because often the very point is to boost the signal enough to overdrive the amp's preamp naturally. Some people prefer time based effects like delay/chorus/reverb in the FX loop, but definitely try both and see what you like.
Of course, some amps don't even have FX loops so it's not unheard of or unworkable to put everything in front. And given that with a multi-effects unit you can't really put some effects in front and some in the FX loop, I'd probably default to the front.
As for amp modeling, that again depends on if you like the sounds you're getting and if you're sure you that never want to use a natural amp tone. I have a Boss GT-6 and while the amp modeling is ok I guess, I greatly prefer a real amp. But again there's no correct answer.
I think a couple specific parts of your question haven't been addressed yet.
if my effects processor also has an amp modeling function, is getting an amp with a good preamp even worth it, if the FX loop would bypass it?
Whether or not another preamp is "worth it" depends entirely on the sound you're going for. It is possible to use the GT-1 preamp (or others) to go directly into the FX loop return, bypassing the preamp. If you like the sound of whatever external preamp you're using and don't want anything else, then no, the amp's preamp won't matter because you'll never be using it. But at that point, you may as well not buy one either. You can get standalone guitar power amps to drive your cab instead of paying for parts you'll never use.
If you go this route, make sure you update the GT-1 settings to tell it that you're going direct into the FX loop.
what affordable amps work well with a Boss GT-1?
This will be entirely up to personal choice as well. The pedal will work just as well with any amp, though the way the amp alters the sound of the pedal (and vice versa) will be slightly different for each amp. This will be especially true if you're using drive, distortion, or the preamp. You'll just have to head into a guitar shop with your GT-1 to try things out and see what combination you like best that also fits your budget. Consider taking your guitar in with you as well to test out your whole chain.
For what it's worth, I run my GT-1 in the FX loop. I use my amp's preamp and don't use any of the GT-1 modeling or distortion effects. I mainly use it for different EQ and noise gate presets for different guitars, and sometimes a bit of delay and reverb.