No way to answer. Any target rifle could fill the bill.
CheyTac, holds world record for target shooting.
For a backstop for your target, an earthen bank.
If you are beginning, I would start with less than long range- a good 22LR target rifle at 100 yards. The skills you learn there will carry over to very long range shooting. Once you have mastered that, the next step will depend on what you call long range. To some people, that is 300 yards- to others, 1200 yards. 5.56 mm ARs, .6mm and .308 bolt rifles are popular choices. Please do NOT start with a .50 BMG or .338 Lapua.
One of the best is a Feinwerkbau Westinger & Altenburger. Biathlon Air Rifle Model P700 Aluminum. Average cost $2,480. It's an Olympic Match Rifle. The best air rifles for target shooting are Olympic Biathlon match rifles.
You will have to buy as many different brands and bullet weights as you can afford and shoot them to find out.
Best to start with 50 grains of 2F for plinking and target. If you are hunting then between 70 and 90 grains 2F will work nicely out to around 150 yards. You will have to tinker a bit to see what load gives you the best accuracy at the distance you are shooting, bit those loads should get you in the ball park.
.22 lr
A Earthbank would be your best bet man.
It depends on weather you are shooting at targets or shooting at game. The scope you choose could be very different depending on the type of target. Tom Gaylord writes some very fine articles on this subject and how to select a scope for the target you want to shoot. See the link below
Something chambered in .50 caliber would be better. But shooting at a mile's distance, success is much more reliant on the shooter's skills, luck and comfort with their tools as the equipment itself.
Depends on the use of the scope - target, hunting, etc. Will also depend on the caliber, and whether firearm or air rifle or handgun. 120 feet (40 yards) is not a great distance (I predator hunt at 500-600 yards) so a very high magnification scope is not needed- 2.5- 4x should be adequate unless you are shooting TINY targets.
You will have to specify if you are talking about rimfire or centerfire.