Yes, all of that staked wood is fuel for the firebox. Since fuel storage space was limited onboard, frequent wooding up stops were required. This led to greater fuel production onshore, with an corresponding increase in manpower. By the 1870s steam-driven log splitters were being put to use producing the four to five foot lengths needed to feed the steamboat fireboxes. One crew manning a new mechanical splitter could far outpace a dozen gangs splitting by hand. As a bonus, each length came out a uniform size and shape.

Soon smaller versions were available for farms and small wood lots. The example of one below is from 1878. A video of a similar one working can be found here.

Can anybody tell me what the large wooden(?) pieces used for that are stacked along the dock at various places? They appear to be too regular in shape to simply be cord wood to stoke the boilers.

across the river?

(Behind the Vienna in the postcard)

Wondering if the piles of wood are railroad ties?

The sternwheeler shown Jas. T. Staples wasn't built until 1908.

http://en.wikipedia.org/wiki/James_T._Staples