Most sellers have been switched to Managed Payments, a system that doesn't currently support the listing and selling of vehicles. So I guess that's why Ebay Motors has disappeared.
The US search thing is an annoying glitch that Ebay is aware of and is currently working on.
When you come across anything new or different, try clicking on the Announcements link, as that generally explains most things.
It's very rare indeed to need to contact Ebay, as everything you could possibly need to know or need an answer to is right here on the site. But Ebay are very easy to contact when necessary. Help & Contact is at top and foot of any page, with Live Chat and request-a-callback available during working hours.
If you continue to struggle to navigate the site, then what browser are you using...? If IE, it hasn't been compatible with any website for ages. If it helps, I use Firefox. Be aware too that if you're using an old Operating System, that may cause issues too, so you may need to upgrade.
I hope this helps, and wishing you all the best.
@yub-tr6
