I've been doing some quick research. In the 1907 city directory, he was listed as having a second hand store at 520 Bridge with his residence at 518 Bridge. There is nothing in that block now that would date back to that time, so those buildings are probably gone.
In the 1912 directory, Wm. Fred. Schmalsle was rooming at 407 Palmer Street while Albert B., Albert G., Edward, Fred, Mabel and Wm. J. lived at 118 N. 5th. I don't recall offhand what is at those addresses now but I can have a look.
The building that now houses the 600 Cafe was the "Schmalsle block," althought I forgot to check and be sure it was named for W.F Schmalsle. There is also Schmalsle street on the north side near the slough.
I'll keep you posted.