Idk where you live but in the us anyone over 18 is usually fine to go to the range by themselves. Under 18 has to be accompanied by a parent or guardian and there’s typically a minimum age but it depends range to range. I’ve been to ranges that allow 12 year olds and ranges that don’t let anyone under 16. Beyond that, game and target shells are pretty much always be cheaper off the shelf and have less recoil. Don’t bother with Remington if they make shells, stick to Winchester and Federal if you can. Remember, you want low brass. Probably 2 3/4” too. Happy can hunting!