I am not totally sure where you could buy a truck like that. First of all you'll need the proper licence like an AZ/DZ or something. You should start in www.Autotrader.com or www.trucktrader.com
You could buy a semi truck at various places such as your local truck dealership. It would depend on your location because different locations have different truck dealerships at different prices.
If they buy it.
You can visit www.TruckCoversDirect.com for a semi rig cover. You shoud also check out the selection at Pulltarps.com.
Yes, but you can't drive it.
Purchasing a used semi truck will save a lot of money compared to buying a new one. You can purchase a used semi-truck at a local auction or at the following websites: www.truckpaper.com and www.truckertotrucker.com/
Buy new truck with new loan.
You can find good deals on used semi trucks at www.autotrader.com.
I'm not sure what a semi-trailer is, but I would imagine a tow truck could help with your problem.
Who invented the Semi-truck?
I guess you could get by with it if you wanted
Yes, you can buy refurbished semi truck parts on the following website: http://www.acmeequip.com/. They have a large inventory.
If the semi truck knocked on the garbage truck, yes.