Yes, all walmarts have a Assembly department that will assemble anything free of charge.

Looking at the bike, you can take an Allen Wrench and adjust it.

Go back to Walmart. Ask to talk to a toys associate or an assembler. They might have another in back or will be able to take one off the same bike.

Go to any bike shops really. You can also go back to Walmart and see if they have any 24' inch wheels in the back. Might not have to pay for then.

24" is the wheel size.

There are no other colors. Just the pinkish color shown.

The easiest way to get a new seat is contact your local walmart, ask to talk to a toys associate or assembler, explain what happen and they should be able to order a new seat. If this isn't possible you can fix the tear with a vinyl repair kit.

yes, I used one when I borrowed her bike last week.

Depends what bearings your talking about. If its bearings for the handlebars and forks, those are universal for bikes. If your talking about the hubs, a normal 24" inch wheel bearings will work. Same with the cranks.

I am 5'3 and my feet firmly on the ground on this bike , it is quite comfortable , Hope this helps your decision