I work for a conglomerate I'll call Giant Enterprise. Answers below in bold.


- Is business class travel OK on transcons and/or international?

I'm entitled to Business only on very long routes, e.g., MCI-DEL. Not to Europe.

- Do you have to fly with a preferred carrier?

We have to use the in-house travel agency but have a wide variety of airline/hotel choices.
- Can you keep your points/miles?

Yes.
Anything else that may be interesting would be appreciated. If you prefer to keep a response confidential, please PM me.

You may be required to use the company credit card for travel. We are. Keep in mind, though, that if you ask too many "mileage-slave" questions they may get concerned that you'll make decisions contrary to the company's interest to maximize miles. One colleague in my business is actually against loyalty programs because of this. Fortunately, I don't work with him.