There is no inner tube and sidewall damage can not be repaired.
Put an inner tube in the tire.
Sure, the inner tube is just a stretchy rubber bladder. It'll expand until the tire stops it.
It doesn't hurt to inflate a tube outside the tire (assuming you use low pressure - you can't inflate it to the same pressure that you could when it's in a mounted tire!), if that's what you are asking. If you are asking about the recommended procedure to replace an inner tube, you want to have the inner tube (mostly) deflated, then put it in the tire and mount the tire. Then partially inflate and deflate the inner tube (so it can move and work twists out). (I usually pull the valve out and go through a few inflate/deflate cycles so the tube can situate itself. Then I replace the valve and fill the tire.)
if the tube is radial too
YES, AN INNER TUBE CAN BE USED CAN BE USED TO SUPPORT RADIAL TIRE, BUT IF THER US SIGNIFICANT SIDE WALL DAMAGE THIS IS NOT RECOMMENDED.
remove old valve & install new tube simple
No
no i dont think so . the capacity of a tire is what it is and using an inner tube would probably decrese the load capacity and be dangerous . you need a tire with a higher load range and max psi .
Rubber- similar to an inner tube or tire.
It's just a small bicycle tire. Use a screwdriver or similar tool to separate the tire from the rim, remove old tube, insert new tube, add air.
No. A 16" tire must go on a 16" wheel (rim).