I'm not a student or a resident of japan so my input isn't worth a great deal but i have looked into this so here's my 2 cents:
Miyagi apartments and houses for rent. Long-term, furnished, serviced and short-term apartments. Many with no key money. English speaking agents.
dorm or private rental?
well i hear foreigners have a tough time finding landlords for private accommodation in the first place. there are specialised estate agents for foreigners but they're not cheap. even if you do find a landlord, odds are, once your 1 year contract ends, you'll find there's no incentive to stay as a contract renewal fee costs like 2 months rent and finding a new place could save you enough money to warrant going through the stress of finding a new place to stay.
id recommend a dorm. less stress and its usually cheaper.
international or uni house?
well you're probably new to japan and unfortunately, the language barrier might isolate you initially from "local" Japanese people so i personally, would play it safe and chose international dorm for a couple reasons. you might find people that speak your language/s and what with you being in a new country and culture, you'll have a lot to talk about. now that's not to say you shouldn't try make local Japanese friends, quite the contrary, you really should, but at least in joining the international dorms, you wont be lonely from the get-go.
id chose international house, but again, that's just what id do.
aoba ward stretches from central sendai waaaaaaay out into the sticks, right to the yamagata prefectural border. ahh on closer look, yeah the dorm is just a stones throw away from campus and has a railway station that goes right into sendai.
in terms of location, it looks good.
in terms of when to move out, idk how long your studies are gonna keep you in sendai but if its more than 2 years, i would max out my dorm stay if i could to give me plenty of time to learn the language and master the art of "alleviating risk" to landlords so id have a better chance of securing housing when the time comes.
be sure to check out this thread.
Post Japanese-related YouTube links here
its a goldmine for info on japan, as is this entire forum
hope you find all that useful. good luck in your studies <3