He would not be a shrimpy kid working for a smithy. He'd need to be capable of handling a single and double jack (sledgehammer) for extended periods. Holding horses that don't want to be held require strength. Mucking stalls is all physical. Forcing metal to go where you want it requires muscles. I'd hire dumb with brawn every time over smart and skinny.
Very unusual for a smithy not to be married. He would be one of the town's leading citizens. Only arguments I'd accept for not being married is the smithy is a drunk or recently widowed.
Why is the general store closing down? More likely if the owner was leaving, someone would buy him out. I'd be more inclined to believe the owner selling out to someone with a big family who doesn't need the kid working there because the new owner has a lot of kids already.
Smithy will deduct the sleeping quarters from the wages, even if the kid doesn't sleep there. But the smithy probably is going to want someone there at night, so that's why the kid is going to be sleeping there. Most smithies would have their shop and boarding stable on the main street (one end or the other, not usually in the middle), while having a house off the main street. This is about economics. Main street real estate is always more expensive.
Where does the smithy eat? Smithy would probably be fine with the kid eating at home, but would probably deduct eating expenses from the kid's pay.
If the kid hops from job to job, why would anyone want to hire him? Western towns were small and everybody knew everybody. If the kid is likely to give me a load of crap, I'll hire a different kid. Hell, I'd hire the town drunk before I'd hire a mouthy kid.
Teamsters did the freighting, either with ox, horse, or mule teams. If there is no railroad into town, every needed to be freighted in. Depending upon the size of the town, it might have its own freighting company, or be served by a freight company that does several small towns. Usually it would be a several day trip from the nearest railroad to a town. Most towns did not have a railway connection.
A smithy would deal with the entire process of a wagon wheel in a small town. As the town increases in size, wagon wheels would become a specialized industry. Here are the basics of rebuilding a wagon wheel. On the outside is an iron rim. This is formed from a piece of iron somewhere between 2 to 4 inches in width, and about an 1/8 of an inch thick. It starts as a flat piece of iron, and the smithy gradually bends it, making sure not to kink it, until the two ends overlap. He then welds the two ends together.
Once it cools down, he would grind or file the inside seam so that it was flat. He would then take the rim, lay it on the ground, and start burning wood around the entire rim, heating it up so that the rim slowly expands. This process would take several hours. Once the rim has expanded sufficiently, the rim is picked up very carefully, and dropped over the wooden rim, where if you've done this right, there's a little gap. Now you let the rim cool and contract. If you've done this right, when the rim is cool, it will be tight. Do it wrong and it either crushes the wood or it is loose.
Spokes are made by finding suitable hardwood branches, which are shaped. They have to be springy enough to pop into the space between the wheel hub and the wooden rim. Spokes are something a smithy would prepare during slow periods.
The wooden part of the rim is made by steaming a hardwood and gradually bending it into shape. The overlap is formed using what is called a lap joint and nails are used to hold it. The hub is also formed from a tree, cut and shaped to size. Advanced hubs would use an iron tube insert for the axle. Primitive ones would just be wood.
Axles are made from longer straight trees, again shaped to size. Axes, adzes, rasps, and patience are the tools to make this happen. End where the wheel goes on should be capped with iron. Fit can be rather loose as these are not high speed hubs. Wheel would be held on by a bolt extending from the axle.
Best of luck,
Jim Clark-Dawe