I started out backpacking long enough ago that I am probably of the old school. I started doing SAR and carrying loads on some sketchy, rocky trails and I found internal frame packs superior in those situations. Gradually I transitioned to the internals for routine use. From time to time I have used a frame for carrying heavy/irregular loads. They do have a place, but internals rule.

Internals are a bit more finicky and proper fitting and adjustment is critical. I would advise renting/burrowing one and using it on a trip to be sure it is right for you.

Down bags are the way to go. They do require care, but you just can't blithely allow a synthetic bag to get damp either. I have blundered and allowed my down bag to get wet exactly once (in fifty years of use). Synthetics do have a place. I'll bet you will wind up with at least one of each. The sleeping bag is the last place where I want to cut corners and scrimp on quality.