If you join a local high powered rifle shooting club, go to the range as much as possible and ask questions. A pitfall in doing this, is that many shooters will only tout the rifle/cartridge combination that they are using! The very least that you can learn, is how the rifle shoots for them. Walk down range when they collect their targets and look at the results. Maybe keep a log and learn which cartridges will fit your needs. Many cartridge/rifle combinations will fit into the plans that you outlined and it is very difficult to pin down what you should get without your checking things out on your own. The shooting range is one place where you can see lots of rifles shooting lots of different calibers and have the chance to speak to folks who are using them.
I know, at our local range, people have shown up that know very little about rifles and cartridges. Most anyone at our range will take the time to answer questions and even allow someone to put a round or two down range. New people coming into our hobby are the life's blood of the sport and most are welcomed and encouraged to become gun nuts, just like we are!