@Tonycarpenter Thank you for your detailed response - much appreciated!
You are pretty much right; with keepers costing one round higher each year, you can keep them through their year being valued as a first round pick. So, yes, Juju is 17th this year, 16th next, 15 the year after, etc.. Thus, the general strategy employed by most is to try to hit with the lower round picks. There are a few big-name players who are keepers, but they are guys who people hit on early in their careers or in their rookie seasons (Odell, Hopkins, David Johnson are the big ones).
For trades, a player's draft round stays with them permanently, so once keepers are assigned and the draft is completed, every player's keeper value for the next year is assigned in permanence, regardless of drops, trades, etc.
My general strategy would be to not keep a TE or a QB UNLESS I have one that is elite. Simply put, pretty much every year you can find a QB who rises from the streaming pile to be a QB1, and obviously TE there is always a few players that hit from the streaming pile. Plus, with this year's rookies, there's probably going to be a lot to go around at TE. Given the positional scarcity at RB and WR, those would be my ideal positions to have my keepers at. However, as you noted, there is such unpredictability at RB that I would probably only be keeping one if it's a guarantee like Freeman.
I'm pretty set with Freeman and Juju. If Juju is a complete dud, I'm fine with it, because his upside as a 17th round draft pick is immense. With Kupp, I feel like he's a definite in a strong offense with QB stability, and I could see him ending up as an Edelman type, strong WR2 each week.
For the final pick, as of now I would say it's between Meredith, Goff and Henry. I agree with you that Henry is top 5 at his position; playing the long game, there certainly is some QB uncertainty there, and Keenan is going to be grabbing his fair share of targets for the foreseeable future. But everytime Henry gets a chance, he produces.
Meredith is a question mark; the sample size is small, certainly. But, if the Bears don't add a big name WR in free agency, even with the draft he'll be the team's WR1 at least for '18. He fits the mold of what I'm trying to get - young players who have flashed in (theoretically in the future) stable offense/QB situations.
With Goff, I really don't know what to think. If he is top 5 potential, then yeah. If he's top 10, you can get those guys in the draft still. Plus, seeing how Mariota, Carr and Prescott were somewhat exposed this year, I'm cognizant of not valuing one year of production for guys like Wentz and Goff too highly. On the other hand, this is the chance to own Goff for his whole career. Take the chance now, and it's a pretty low risk to dump him in the future. The big issue with keeping Goff, though, is that there really isn't a QB premium in the draft with only 12 people and one starting QB. You can get guys in the 5th/6th/7th rounds pretty easily.
The other issue with the draft is that it can be tricky to keep 4 WR, for example, because you might end up having to reach for an RB at your draft position. That's why my ideal mix would be RB and WR so that I can take one or the other, get the best available, and still have some depth already there.
I would recommend a keeper league - it's really fun in that you get the redraft aspect and the dynasty aspect all in one. Everyone is trying every year to win it all, while trying to build for the future as well. When you hit on a keeper, it's awesome. The draft is really fun as well because there are so many players who are out of their slots and moved down - really takes a lot of planning to get it right.
Again, thank you for such a detailed response!