I had dirt bikes my whole childhood the savage is my first street bike so i was wondering what is the average time duration between oil changes you recomend? also i need new tires i used to do them myself on the dirtbikes do i need to pay someone to mount and balance them or is it not a huge deal also should you replace the tubes at each tire change?  

u need to change your oil more than once a year!!  unless, u got a "show" bike,in that case id just push it around,no need to waste oil , as for tires its just like dirt bike tires ,but u use a little more muscle. and becareful to not chip the chrome.

Oil change here around 6 to 8 weeks

First thing - My advise is to change the oil between 1000 and 2000 mi. or every 6 mths. Of cource You can change it once a year or if You want -once every couple of years. This is Your bike. I personally change my oil roughly every 1000 mi. and the oil filter every 2000 mi.
About the tires- on the dirtbikes is harder, because You have tire locks and usually You use heavy duty tubes. You decide about the tube when You take the tire off. I'd say - if it is not leaking , it is OK. There will be a lot of guys who will tell the oposite. The only diff , compared to the dirtbikes is that Here on the tires You usually have a directional arrow, that has to follow the direction of the rotation and also You will have a dot /yellow or white /, that has to line up with the valve stem.

I'm using a pure synthetic and change it between 1500-2000 miles.  If I were running dinojuice, I'd change it at about every 1000.