RE: Good long-range deer calibers.
If you can't do it with a 30-06 then a 300 aint gonna do you any better.
I certainly would not reccomend a Benelli R1 for a first rifle. There is a lot of maintenace that goes with a gas operated semi auto rifle and semi autos are mush more prone to malfunction than a good bolt action.
A good bolt action rifle will serve you far better than a semi auto for a first rifle. They are simple to operate, ultra reliable, easy to maintain, and generally more accurate.
Honestly a 30-06, 280 or .270 would make a much better first rifle than would a 300.