In order to 'dial for the distance' you will need to know the amount of drop your bullet has at a given distance, then adjust your scope 'up' the appropriate amount in order to compensate. The Bushnell adjusts in minutes-of-angle (moa). Most software programs will give you the adjustment in moa. It's not too complicated. Doping the wind...now that gets complicated.
Yes, you will need bases and rings to mount your scope on your rifle. Given the long distance you want to shoot, you will want to look at canted bases. That is to say a base where the rear of the base is taller than the front. With your scope canted, it will give you more adjustment 'up' than if it were mounted level.
The alternative to a canted base is to use Burris Signature Rings. They employ inserts of varying thickness in order to cant the scope.
You can find info on Burris bases and rings here:
Burris Signature Rings