Matt: As Dennis alluded to, Miami would indeed get two first round picks if another team signs Landry since he has been franchise tagged (Non Exclusive allows him to talk to teams). However, also as Dennis pointed out, there is no way a team will surrender such a price tag for really any WR these days. I don't necessarily agree with Dennis about only being able to get a 2nd Round Pick in return for him, as Landry is like the only third player in NFL History to catch 400 Passes in their first four years in the league. Certainly, a 1st Round Pick has to be in play, even if, like you mentioned, is a Late First Round Pick.
As for Buffalo, it's because they do want one of the QB Prospects. I understand where they are coming from, since some GMs don't really care of either Cousins or Keenum. If they believe one of these QB Draftees could end up being their Franchise Signal Caller, then I see no problem trading up to get him.
When it comes to the QB prospects, I really don't like any of them. If I had to pick just one, I guess I would personally go with Darnold. Mayfield will never have that strong of an arm, but he's a bit of a hot head due to just how competitive he truly is. However, he can galvanize a team better than any of the other prospects. Jackson is another polarizing player; some say he could be like Michael Vick (but even better), while some GMs believe he should switch to WR. Rosen is the most ready of any of the QBs, but he is a California silver spooner that has character concerns on whether he NEEDS and LOVES the game of Football. Darnold has a bit of a weird throwing motion, but his arm is extremely strong and he is really accurate. However, he threw more than 20 INTs last year, which gives you some concern. Allen played at a small college, meaning he didn't play the level of talent as the other guys. He has the strongest arm for a prospect in the last decade, but he is extremely inaccurate most of the time. Other QBs like Falk and Rudolph are pure passers, but they will be nothing more than Career Backups.
If I had to guess, Allen, Darnold, Rosen and Mayfield will all be taken in the the 1st Round. Jackson has a chance to do the same, but some GM would have to fall in love with him being a raw QB Prospect. After those five, everyone else is a Backup at best, maybe a spot starter like Matt Moore has been for the Dolphins over the past five years. But that's it. Again, I would pick Darnold out of all of them if I had to; however, I would rather have Cousins outright.
Dennis: I don't really agree with your assessment, but that's okay. In my eyes, Luck has the POTENTIAL to be a Top 10 or Top 5 QB; however, as his stats show, he's a bit of a pick machine. I think his TD to INT Ratio is like 2-1, which is dangerously close to Favre Land. Couple this with the Shoulder Injury - no matter how much his new doctor would like to give a positive prognosis - and Andrew Luck is as much of a question mark as, say, Ryan Tannehill.