Around here, it would probably be called Victorian Farmhouse.

Saltbox and farmhouse are building form and use descriptions that can be independent of architectural styles although most of them were derived from Colonial styles and if that is the case (not enough photos to know) this house would more properly be called a Colonial Revival which would have been popular in 1904 even if the interiors retained some late Victorian detailing.

I wonder if the room over the porch wasn't added later.

Forgot this link

Here is a link that might be useful: Colonial Revival architecture in Oregon

Looked at the house via satellite and my question is: not including the area over the front porch how many rooms are there upstairs and down? Downstairs - front parlor, LR, dining and kitchen with 3 bedrooms upstairs and bath or similar?

From the roof line, etc. I believe you have a modified American Foursquare (i.e. different regions tweeked the "normal") with an upstairs sleeping porch (used during warm weather prior to a/c) that got partially closed in during a later remodel. The dormer window would have been removed with the remodel.