Taxis from arrivals to local motels?

All available. Even the Sound transit train into downtown

Yes, follow public transportation signs

Yes

Yes. There are a myriad of ways to get to and from SeaTac. A lot of local hotels/mltels have shuttles, taxis, uber, and public transportation are all available.

Absolutely. You can also use uber or lyft. Ask if your motel provides free shuttle service :)

Taxis, Ubers, and many hotels have shuttles.