It has been my experience that most Indonesian/pacific rim coffees are low in acid. Examples would be Sumatra, Sulawesi, Java, Flores, Timore-leste, Papua New Guinea. I'd also have to mention coffees from India as well.
This is an individual question with no real answer.
Personally, I prefer Indonesian coffees (not Sumatra, but Flores and similar) or lesser known African coffees from Uganda or D.R. Congo when I can get them. I also prefer roasts of City+ or occasionally Full City.
That probably doesn't help...
It can if you are not used to that much caffeine. If this is your first experience with fresh roasted, especially a light roast, you may be getting more caffeine than you are used to.
You can certainly buy green beans from a wholesaler. I wouldn't recommend buying roasted from a wholesaler, it wont keep long. I know of one wholesaler that sells to the public in small(ish) quantities. See link below.
That said, you wont get much of a break in price, unless you buy in bulk...
I had a Technivorm Mocha Master for a few years. It's a very good drip machine. I eventually replaced it with a Behmor Brazen + 2.0 (they are now 3.0). This is noticably better auto drip. It has a pre-soak step for the grinds, and you can program the temp to exactly what you want. I've been...
I would say try as many coffees from different origins as you can. We all have our preferences, and not all coffees no matter how good are liked by everyone. Try to get a feel for what's out there, and there's a lot out there. It may take time, but you may find quite a few that you really like...
Some people's first experience with coffee, especially whole beans is Starbucks or Peets. They do tend to learn towards darker roasts, so that's what people are used to. That said, some people like darker roasts. Also, some beans taste better with somewhat darker roasts.
Sometimes its just really hard to hear the first crack, depending on the beans. Other times and other beans, you can hear it from another room.
I don't roast in a pot, so I can't give you better details, but keep at it and you'll get the hang of it.
I've been using a Behmor 1600 since they came out. It will roast a pound of beans unless you like it *really* dark. I rarely go into the second crack, so that's not an issue for me.