The short answer is yes. The course and certificate are acceptable to every county sheriff in Oregon
The longer answer is that the sheriff does not set the requirements, they are set by Oregon state law, and there are more acceptable qualifications than are typically listed on the various sheriff's websites. For a complete description of what is and is not acceptable refer to ORS 166.291.

Yes, you can. The login name you receive will be the same for each person, but the passwords will be different. The system identifies the particular user by the username-password combination. Note that if a second person tries to login on the same browser that someone has already used for a course, you will see that first person's training session. To start a new session you will need to destroy the cookie that the browser holds to indentify the training session and its status. You can do this either by clicking on the "Logout" button (below the navigation controls), or by closing the browser and re-opening it.

Oregon doesn't place any restriction on when safety training has taken place, so for the purposes of an Oregon CHL the certificate is valid indefinately.

Well, if it it was, I would be the last person to ask :-)
You might ask around, I have delivered courses to 8,004 people in Oregon and many in adjoining states. On the prices, I set them deliberately low. I am more interested in helping people to obtain their CHL than I am in trying to get rich from those people. My name appears on the instructor lists maintained by several county sheriff's departments, if that helps with credibility.

There are no hidden charges, fees or whatever. The price you see is what you pay for training and a certificate of training. Unlike some, I do not have people complete the training, then ask for an outlandish sum to issue the certificate.

No. The principal reason is that I do not consider these classes to be good value to anyone living and travelling in the western states. There are better options, which the same course and certificate for the Oregon CHL will qualify you for at no additional cost. There is a lot of hype around the Utah license. Look at the alternatives (e.g. AZ and FL) before spending your time and money on a Utah course.

Oregon only permits out of state permits to residents of adjoining states. That is, California, Washington, Idaho and Nevada.

Mostly because it is a large and complex topic. Even in the in-person course, the most I can really do is to give an introduction to the basics of firearms law and use of force topics and discuss how misleading it can be to simply read the statutes as written. Whatever you may read on the Internet or "learn" in other courses, you are not going to be fully prepared to understand every nuance of every applicable law and how those laws get modified in practice by layers of case law. To even try to cover this in an on-line course would be at best incomplete, and at worst, downright misleading. There are good reasons why lawyers who have spent many years dealing with these topics can still disagree with each other and be surprised by how cases that reach court actually go.

You may want to consider either taking the in-person course, or perhaps buying the book on the subject written by Kevin Starrett of OFF.