Re: first gun
My vote would be the 7/08 (A 308 necked down to 7mm). or the 260 Remington (A 6.5 x 08)
Plenty of ammo, lower recoil than a 308, better ballistics with lighter bullets, an easy 600yard+ cartridge for hunting, great accuracy to a 1000 yards, short action, And does not need a barrel longer than 20 to 22''.
The youth model in Remington has a shorter stock and comes in a Model 7 (A short 700).
Savage also chambers the 7/08.
Just my opinion
J E CUSTOM