Mid Plains,
First of all, welcome to the boards! And congratulations on your upcoming elk hunt!
Second, always check your sight in when you arrive in elk country, but not for altitude adjustment, but just so you know in your heart of hearts that the rifle is hitting where you left it on leaving home. Look at the numbers on the quoted 9,000 foot elevation swing....
30-06 165gr Interbond load: 10,000 ft elevation
yards velocity energy ftlbs drop
0 2900 3081 -1.50
100 2747 2765 1.56
200 2600 2477 0.00
300 2457 2212 -6.65
400 2319 1970 -19.06 ....
30-06 165gr Interbond load: 1000 ft elevation
yards velocity energy ftlbs drop
0 2900 3081 -1.50
100 2691 2654 1.66
200 2492 2276 0.00
300 2302 1941 -7.21
400 2120 1646 -21.12 ....
So,
0 yards, no change
100 yards, 0.10" difference (common range)
200 yards, no change (common range)
300 yards, 0.56" difference (long shot)
400 yards, 2.43" difference (damn long shot)
IMHO, out of all the things that can cause you not to get an elk, I would list this as being one of the smallest; however, it does make for suitable fodder for a benchrest discussion. If you are still concerned about it then take a handful of 200 yard shots when you do your scouting trip at altitude so you know in your heart of hearts that it is essentially a non-issue.
Assuming (ouch) that you have taken some of those Nebraska deer and know what to do with them once they are down, .... the main adjustment to be concerned with is your own physical conditioning, it don't necessarily take all that much, but start working out early. If you can't get into what you think is the proper shape, then be sure to level with your guide/host/self with plenty of time in advance to allow for an attempt to accomodate your limitations....
Equally important is your "attitude adjustment".... bring all your mental toughness and tenacity with you and figure on a fair measure of physical and mental discomfort before (and after) you receive your reward. Persistance and a "can do"/"will do" approach will take you a long way in spite of other possible short comings. I had two Nebraska boys in camp last year, both 58, one with asthma and one with arthritis and they both did great ---- you can too.
I'll leave it to others to address your other "area specific" questions....
Good Luck and Good Hunting,
EKM