DeerHunter,
Congratulations on your new rifle.You made a great choice.The 30/30 is one of the best Whitetail cartridges that is avilable here in the USA.
The choice between the 150 grain and the 170 grain bullet is similar to your choice between a Redhead and a Blonde.My favorite is the 170.
Ignore anyone who implies that you need more practice with your 30/30 then you would need with a heavier gun.If you ever get the need for more speed,you will need just as much pracice with that gun also.
As far as the limit of extreme range of your ne rifle,it is determined by you,yourself.The cartridge will kill a Whitetail at 200 yards,but at longer ranges,you have to be an exceptional shot.
I made an instant kill at 100 yards,and I witnessed my Buddy make one at 125 yards.That is MY limit with this cartridge,and I suggest that you keep within that range,until you are sure that you can do better.
I hunted for 50 years with various "bolt guns",and the 30/30 is doing just as well as any of them.(so far).
Good luck,
Frank