Do I need a pack? What type and size?
Absolutely! You need something to carry rain gear, socks, candy bars, ammo, camera and assorted
amenities.
There are two main types, external frame pack and internal frame soft pack. In either case don't get anything small. The weight of the material is insignificant and you don't have to fill it up, but it's there if you need it. Most guides will be using an external frame pack because they are better for heavy loads than a soft pack. I find an additional advantage to an external frame pack is that I can attach a rifle carrier to the frame freeing my arms up for glassing and pushing aside alders. Not all rifle carriers are created equal. The best I have found is the Rifle Packer. It's made in Fairbanks by Dark Horse Leather for Alaska hunting so if you desire one I can arrange it for you. At last check they were around $40.
The other alternative is a good internal frame soft pack designed for the mountaineers. Probably the most suitable for a hunter who is not required to pack out meat and antlers. Don't get the average daypack. They are small and the suspension systems in them are uncomfortable over a long period. They are fine for carrying your lunch to a deer blind but not for serious use. And don't worry about the color of the pack. Buy a set of dull spray paint (they usually come in black, brown, olive green, and sand) from a hunting supplier and spray everything visible. Use a branch or a few leaves as a mask and you will be surprised how good it looks. For a more complete description I will send you an equipment list and comprehensive description of every piece of equipment listed when you book a hunt. If you follow it you will be well prepared.