From PDX (and Eugene) to Corvallis:
HUT Shuttle (easiest although more expensive option, connects directly the airport to Corvallis): http://www.hutshuttle.com
(you can ask the driver to reserve you a cab once in Corvallis to go to your hotel). There two stops in Corvallis: Hilton Garden (South of Campus) and Longhouse (on Campus). If you are going to call a cab the Hilton Garden is an easier solution.
Greyhound Bus: cheaper, comes directly to Corvallis, but you have to go from PDX to the bus station downtown from the airport. This link shows examples on THURSDAY EVENING: https://www.greyhound.com/en/ecommerce/schedule
There is no train station in Corvallis. There are some bus connection or train + bus connections. The closest train station is Albany. But from there you would have to check buses to Corvallis.
If you are flying into Eugene Airport, you can take the Omnishuttle to Corvallis (http://omnishuttle.com), although it is fairly expensive – or you connect with the presenters coming from the University of Oregon, which is in Eugene, and try to arrange something together.
Moving around in Corvallis:
Corvallis is a fairly small town and you can basically get everywhere walking (max. 30 min) in the areas around Campus & downtown. Buses are free, but not very frequent (http://www.corvallisoregon.gov/index.aspx?page=167)
Directions and Information for the Conference Days
Here you can find an interactive map of Campus: http://oregonstate.edu/campusmap/
Search for Milam Hall (where the conference sessions & the keynote are scheduled) and for Autzen House (the Center for the Humanities) where the opening panel discussion will be held.
Registration opens in Milam Hall (3. Floor in front of room 319a) on Friday at 9:30. Sessions are all in Milam 319. The Keynote will be on the ground floor of Milam Hall (Auditorium).
Right north of Campus (Monroe Ave) you can find cafés, bars, places to eat and hang out, if you stay near campus. If you are staying near downtown check mainly on 2nd and 3rd street.