A 22 can be a good start, learning marksmanship is easier usually and there are plenty more places to shoot them. Bolt or semi? Bolts are more accurate, does Purdue have a shooting team? In JROTC I learned some good basics with the 22s they had. Wish I could have joined the team though, all of them were shooting Expert before the end of the semester. If not, the NRA has some excellent small bore classes and often you can borrow or rent a rifle for them. Read the Military Marksmanship Manuals, they are excellent sources of the basics.
You will probably will shoot shitty but with practice you WILL improve.
Welcome to the sport and thanks for being in the ROTC Program.
As for 10/22s, they are fun to build, relatively easy and parts are plentiful. Unless you find an excellent deal used already built I'd suggest building your own. There are so many variations and parts that it is hard to find exactly what you want already built.
Check out rimfirecentral.com, plenty of info there.
I'm not familiar with Stafford, but if you don't rush into buying and do some research you can gain a lot of knowledge before buying anything.