Welcome to RCNT!! All in all that's pretty good advise, but the first thing I would strongly recommend you buy is an in line fuel filter and a high performance air filter (Motor Saver is a good one) and your LHS should have both of these items on hand as well, you will probably spend about $30 tops on the 2 of them, the 25 already has a good set of dogbones in it, if you are going to upgrade the dogbones I would suggest getting M.I.P. CVD's, they will transfer the power to the wheels much better than standard dogbones, though this upgrade is one that can wait, I would say the upgrade on the servo could wait until you absolutely need it, I have Jumbo Kong tires on my Savage 25 and the stock servo handles them with ease, the hump pack is a great suggestion, you really don't want to have to open the rx box unless it's really necesary to do so since it is a real pain in the ass to open and close the box..........the diff mod could also wait unless you really want to do it, you can however put the gear oil in the stock diff's for the possi track action, I am going with 120,000 weight in mine.
OK, now something that usually breaks for newbies is the "one way bearing", this is a bearing on the rear of the motor that turns the crank to start it, if the engine floods while you try to start it and you keep trying to crank it thus putting a lot of strain on it, the bearing will fail and you will be spending about $18.00 for a new one, the very best advise I can give you is when you get the new Savage home before you do anything else READ THE INSTRUCTION BOOKS FIRST.........mainly the smaller of the 2 books that covers your engine, this will tell you how to break it in correctly, if it gets confussing we are always here to help you in anyway that we can, hope you have much fun with your new Savage!