As far as roasting equipment... I actually recommend starting with stovetop/pan roasting. You may struggle more to get an even roast vs buying an appliance or using a popper, but it's cheap, and pan roasting heats via conduction (not convection) which is the de-facto method of most roasteries.
450 degrees F for 10-12 minutes (you can eyeball the beans will get you started).
I've used a few vendors for the green beans but will recommend https://www.coffeebeancorral.com/ (no affiliation). I usually buy beans in the $40 (shipping) / per 5 lbs.
You'll have to deal with chaff but as you go forward you can get into more elaborate options. And to be honest I end up grinding a not insignificant amount of chaff (it doesn't affect flavor).
This is bad advice. I really can’t recommend this.
If you’ve ever played with home rosters with larger capacities, you’ll quickly find out just how much smoke gets generated. It’s a sticky and oily smoke too.
You don’t want that in your home.
Either you’re outside, or buy something like a Behmor that has an after burner.
Fluid bed roasters dissipate the smoke much faster compared to drum roasters. I used to use a small fluid bed with some concertina tubing and a lot of filters to pipe the smoke outdoors. That tubing got very dirty. I never saw any smoke from it. But you can smell it and it’ll trip your smoke detector.
I’ve never heard of any one recommending the oven as a first attempt. Usually it’s a pop corn maker.
I’ve used several home roasters. Getting one with an afterburner is the way to go unless you have extremely good ventilation or powerful range hood that vents outdoors.
That's extremely surprising given the first handful or so of Google results suggest it (along with the popcorn maker)
Unless you're going for a French roast in a small, unventilated room this is not going to be an issue to worry about.
Yes, you could trigger your smoke alarm but that happens if I cook a steak, too. When I used an oven I think mine went off once or twice from dozens of roasts.