Tom address your first question: The safety position last year didn't suffer injuries four-deep.
If a game-changer safety were available I'd take him, as good OL help might be available later. We need depth and developmental players in the middle (and a good, sturdy, proven journeyman C if one should fall into our hands) and have a question mark at LT. WE don't know what a new OL coach will bring to our rteturning crew of starters at four out of five position, who were plenty good enough to get us a ring.
That said, I wouldn't pass another Humphrey for another Yeast. Would anybody? (Maybe for another speedy little wideout, but that's on McVay, not us.)
I'm a big believer in having a strong and effective offensive line, but we can't base our approach to this year's OL solely on last year, when all of the OL starters, save for RT, were gone and the subs were four-deep and taken off the streets. We need to be deliberate. As fans we tend to panic. We need to relax, and let Snead do his work. In our Super Bowl year we thought he was a genius.