Depending on how much he eats, you can keep some in the fridge too. There's different sized boxes (1lb, 9 lbs, 31 lbs), with a negligible price break in quantity, so there's some flexibility in the freezer space issue, unless your freezer is actually full-on jam packed.
Not sure how other brands package their portions, but the brand that we sell, each pound is separated into 4 portions, and packaged per pound. (4 x 0.25 pound portions in each package inside the box.)
For example.. If your dog weighs, for simplicity's sake, 33 pounds, then he should eat around a pound a day. So what most of our customers do, if you buy, say, a 9 pound box, you can load 3 packs into the fridge to start, and the remaining 6 into your freezer. And every day you finish a package from the fridge, put a new one into the fridge from the freezer. It may sound a bit tedious, but once you get the hang of it, it just becomes routine.
I share a regular fridge with 2 housemates and we do just fine.
In terms of transitioning your pup, mix a chunk of raw food into his bowl of kibbles and see if he eats it. If he likes it, you can probably turn him onto the raw food diet right away. If he's a little uneasy, continue to mix in more and more raw food everyday with smaller amounts of kibble until he's only eating raw food.
Hope this helps