Cherriots offers bus service in the Salem area, but a more extensive area served less frequently is operated by a service called CARTS - The Marion and Polk County Public Transit Service. The only information about this service available on the web is located on the Cherriots web site.
There are several buses each week work day (weekdays excluding certain holidays) that run from the Salem Transit Center through Silverton and terminating at Mount Angel. This is CARTS bus route 20, and it operates four times per day going from Silverton to Salem, with the continuation to Mount Angel only being offered once per day.
Standard fare as of this writing is $2, with discounts for certain groups (children, elderly, etc.). A day pass is $4.
Downtown Silverton is congested enough that they do regulate parking. The parking meters are cash only, so it would be good for you to have a few coins if you plan to park in the central downtown area (which includes only several blocks).
The meters may be new electronic meters, or as of this writing there are several of the old mechanical meters left.
The old mechanical meters give 12 minutes of parking for 1 penny, or two hours for a dime, or an hour for a nickel.
The new electronic meters do not accept the penny. Instead, they are more expensive: one nickel buys only 12 minutes of parking time with those types of meters.
Mostly, this is done to regulate the parking availability, and make sure no one hogs the parking spaces. Certainly, it is a bargain compared to parking in many other cities in Oregon with paid street parking! However, you do need to be prepared for it and make sure you take a few coins.
As in many other cities in Oregon, the parking meters are "closed" on Sundays. Sure, you can still put your money in and they will still run, but there is no parking enforcement. So, on Sundays you can be treated to an even larger parking bargain.