MOA = minute of angle. It is a unit of measurement. As you look at scope specifications you will see that most have 1/4moa ("click") adjustments. At 100 yards, 1moa = 1.047 inches. So a 'click' of the scope is about 1/4" inch. As the distance goes farther 1moa changes. For instance at 200 yards 1moa = 2.094" (2x1.047) at 300 1moa = 3.141 (3x1.047) at 1000 yards 1moa = 10.47". (given that .047" is so small, it is generally accepted that 1moa=1" at 100 yards and so on)
So let's say for instance you shot a target at 200 yards and your shot was 3" high and 1" right. I would tell you to adjust your scope 1.5moa down and .5moa left. Since 1moa at 200=2" that would means 1.5moa=3" and .5moa= 1"....make sense?
For shooting long range you will not 'hold-over' on the target. You will dial the scope up to compensate for the drop at that distance. For instance, a .308 zeroed at 100 yards will drop 380 to 400 inches at 1k. Since 1moa at 1000 = 10" you divide the 400 by 10 and you get 40moa. That's how much adjustment 'up' you will need in order to shoot 1k. So you can see that a scope with 20moa total adjustment just won't reach that far.
To resolve this issue, you want a scope with 60 or more moa total adjustment and then you want a 20 or 30moa canted base (one where the rear is 20 to 30moa higher than the front). With this set-up your 100 yard zero will be at about 10-15moa from the bottom of your scope adjustment. This leaves you with 45-50moa 'up'. In the case of my scope where I have a 30moa base and a scope with 80moa I have about 60moa 'up' from my 100 yard zero. This set-up will shoot beyond 1k.
In terms of magnification, I have no problem shooting 1k with a ten power scope. The conventional wisdom is to use a higher magnification. It's a choice that's up to you. Personally the scope I chose has sufficient magnification to shoot 1k, it has great target knobs for easy adjustment, it has a mil-dot reticle and it didn't cost a fortune (you can spend a lot...and I mean a lot...of money on a scope if you want). I didn't make my decision blindly. The scope on my 308 was reviewed on this website...
Low Priced Long Range Scopes
A friend of mine is looking for a new scope for his 300mag. His intent is to hunt elk at long range. He doesn't have a ton of money, so he's found a good balance of dollars (~$500) and performance with this scope....
Sightron Riflescopes / Binoculars / Sighting Scopes product pages. SII Series - Big Sky - SIIB SS 4.5-14x44 MD
Remington vs. Savage...that's an issue that will be debated forever. Personally, I have remingtons and I have friends with savages. I find that the answer to which is better is up to you.
Here are some pics and specs on my .280....
http://www.longrangehunting.com/forums/f53/my-280-a-32771/ It is a good example of a rifle that will hunt in the woods (up close and personal) and make a long shot.