As stated, food is readily available so no need for additional freezer. Yes, the ferry is expensive but if you can afford it for one-way, the scenery is fantastic. However, definitely drive the return trip. The land is beautiful, too. Safety? No problem. We mainly boondocked not far from the highways and sometimes alongside. You'll see many RVers doing this in fantastic spots. Reservations? The only ones recommended are for the July 4 weekend and staying in Denali Nat'l Park. Those can be had at only 3 weeks prior when you can better judge where you'll be when.
Hopefully this post will be moved over to the Canada/Alaskan forum where you'll find much information by looking on the 'Sticky' at the top of the page for past RVers suggestions and also on the current thread going on of those traveling this summer 2014.
Alaska is just like traveling in the lower 48 two-lane backroads. You'll be just fine. Millions drive it and you'll see many of the same folks along the way.