You most likely will match in Family Medicine as long as you apply and interview at enough places. It's not a competitive specialty. Even if a Family Medicine program has spots in the scramble, that does NOT mean it is a bad program. Since there are so many spots in family medicine, sometimes even a good place may go unfilled.
You certainly can scramble into a traditional rotating internship - though my advice would be to rank some TRIs on your list below all your preferred family medicine programs so that if the FM spot doesnt work out you may match into a TRI spot anyway. Scrambling is extremely stressful. You will be under pressure to accept the first spot you get offered even if it is at a place you don't like just to make sure you get a spot somewhere. I had to scramble, and it was some of the worst few days of my life. I took a gamble by holding out for a spot at a place I liked even though I had offers come in sooner from less desirable places. It was horrible trying to decide whether to take a spot I wasn't thrilled with but that offered security vs. taking the risk of being left with absolutely nothing (all while still reeling from the shock of not matching at the places I had spent months getting attached to!). I absolutely recommend ranking as many programs as you can and doing everything possible to avoid scrambling.
No, you don't have to complete your residency at the same place you do a traditional rotating internship. The internship by definition is just a one year commitment for both you and the residency - no promise on either side of anything for second year.
Choosing a residency is something of a crap shoot. Going on interviews, you can't be sure that the image of a program that you get on interview day is really an accurate depiction of what working at the residency is like. The program isn't going to let you meet disgruntled residents on interview day.
You may also want to consider that just because someone who scrambled into the program is unhappy, that doesn't mean the program is bad. Having to scramble can be a very disappointing thing for someone who had their heart set on a place they interviewed at. I can definitely see how scrambling could make someone feel bitter, even if there is nothing really wrong with the place they wind up scrambling into.
However, even ending up at a less than ideal residency program still means that, as long as you stick it out, in the end you will be a fully licensed physician, so it is important to not lose perspective.
There certainly are good AOA FP residencies out there. Even though FP is relatively non competitive, some of the programs within FP must be more competitive than others.
Whether the ACGME FP programs are "better" is a very complicated and politically charged question. Chances are, the best AOA FP program is much better than a bottom-of-the-pile ACGME FP program.
Trying to get an ACGME FP program is a risk, though. The AOA match happens first, so if you don't get an ACGME program, you are left in the ACGME scramble or trying to get something left over from the AOA match and scramble, since it happens a few weeks ahead of the NRMP match.