blade runner adventures chi siamo
"What snowboard lenght and shape is recommended?"

It is for sure a choice quite personal, but you must consider that you will be riding mostly in deep powder, so that shapes like "rocker" or "swallow tail" can help a lot.
Lenght recommended varies from at least 160cm for mixed terrain (open alpine and trees, Canadian typical) to 185cm for huge Alaskan runs (no trees up there).
However at Chugach Powder Guides, Alaska, snowcat run are mainly in wide but steep trees, so that bringing 2 different boards is not a bad idea.

"Should I bring my skis and snowboard or can I hire them once up there?"

In principle it is possible to bring your own gears, but you must consider that almost all organizations offer modern freeride skis included in the package price, while snowboards and telemark skis are not.
Our suggestion for alpine skiers is to birng only your boots as cabin luggage, while for the others is highly recommended the whole gear set.