I think your on the right track with all of your research, and the suggestions are as well. The only thing I can't or don't understand is your reference to an "external frame pack". If you plan on hiking in any rough country, or any rough trails, the external frame pack will not help your experience. The point being that to hike comfortably over varying degrees of terrain it is essential that your pack be capable of comforming to your movements. The external frame will fight you with this. The new packs with their framesheets, stays, or lack of large frames, will provide all the support you need at the weights you plan on carrying, and will allow you the mobility you need on the trail to keep you moving steadily, and safely! I can't really think of any reason for a true external frame back in this day and age (outside of pure weight carrying circumstances, e.g. hunting) There are many places that even allow you to rent a pack to try out. Put some on and give them a go! And there is a constant parade of used packs for really good prices on all of the forum buy/sell sites. Avail yourself to the technology, its not new, nor is it untested.
Finally, have a blast checking out and finding your gear! Its a great way to become educated and to enjoy trying out new ideas to make your trips fun! At all costs, try to keep an OPEN MIND with regards to what folks are using and enjoying. My packing techniques and equipment has mutated a ton over the years, and have increased my pleasure in the backcountry immensley.