Welcome! The Bicycle Blue Book website has a picture of it. They don't list any monetary values, but given the picture and your description, I think it's pretty clear what you have. Yeah, it does look about like an FX1 plus a telescoping seat post and an adjustable stem. The components look pretty basic. It looks like there's probably a 7-speed freewheel in the back. The Weinmann rims are good entry level rims and the generic Chinese tires are probably fine. That same factory might make other brands in a different label as well. I'm sure you can fit wider tires on it, but you'd have to measure your frame to be sure. The there are three basic places to check:

1. Fork.
2. Seat stays (where the tire passes through the two tubes where the rear brakes are mounted).
3. Chain stays (where the tire passes through the two lower rear tubes.

It's likely to have enough room for 35-38mm tires in those areas, but check to make sure.