You can buy them over the 'net, from any number of sources. Or a well-stocked bicycle shop is likely to have some in store.
My first bicycle, made in the 1930's, had wooden wheel rims.
One can shop for BMX rims in bicycle parts selling stores. One can find these stores in bicycle selling stores. Also, one can find them online at websites such as eBay or Amazon.
Friction which causes heat.
You can get bicycle wheels with aluminum rims, from about $150 and up, but solid aluminum wheels gets too chunky to be used on bikes.
Sure. Keep it off tires, rims, brake parts, saddle and grips though.
Bicycle rims are NOT aerospoke specific. Any wheels can be laced with either round or "flat" areospokes. If you require a rims replacement; contact your LBS (Local Bike Shop) for the current options. If you're building a new bicycle wheel using aerospokes; be aware that not all wheel hubs will work with every aerospoke brand/make- as they are size specific. Your LBS can explain your options.
No you do not.
No, rims and tires are separately priced items.
Yes, you can buy tires and rims together. It wouldn't be considered as a package because tires and rims are sold seperately. They are not an item sold together.
There are a few Giant bicycle models that have 26 inch rims. They are the 'Revel 0', 'Revel 1', 'Revel 2', 'Revel 3' and the 'Revel W'. One can find stores to purchase from on the Giant website using its store locator.
Try Custom Wheel.com I believe they sell rims that way.
No. You'd have to buy an adapter