You should never completely drain an above ground pool. The chemicals in the vinyl liner that allow it to stretch when originally installed do not last. If you drain the water, the liner will shrink and when you refill the pool there is a good chance that instead of stretching back the liner will rip instead. NEVER drain your pool.
I have a in ground pool. I fight a mold that is white and thick in the pipes.
Sometimes it is slimy. My water tests are just around nomal.
Yes
The overflow is built into the sink, it is not part of the drain. If there is no overflow, you can not add it.
Pavers should drain away from your pool.
you should drain it using your mouth
If you have a stink coming up from the overflow drain in your bathroom sink, you have some garbage down there that you should not have. You probably have a lot of hair clogging the drain. It is probably slow draining. You need to clean it out and get rid of the gunk.
Most of the one's I have run across do not have an overflow. Mainly used for disposal, dumping out drinks, etc, not for washing so overflow not really an issue. Also, most are stainless which do not lend themselves to an overflow drain.
You should wipe were the kid vomited and clan the pool with pool chemicals but if it is really bad you should drain the pool cleean it the fill it back up.
Usually. Going through the overflow drain gets you straight into the drain without having to make the sharp bend in the tub drain. There could be a trap that comes apart in the drain underneath if it is accessible.
In my experience, I would say no. Several reasons can prevent the overflow from working. Since the overflow of the sink is rarely used it has a tendency to be blocked at the lower portion where the sink joins the drain pipe. During normal use and over years the holes in the sink drain at the point where the overflow and drain pipe meets has a tendency to clog making the overflow drain slowly. You can notice this when your sink drains with a "gulping" sound. You can test the overflow drain and see how obstructed it is, but do it slowly and do not turn on the faucets on full.
Yes, the gasket between the overflow pipe and the tub can go bad, or it can leak around where the pipe is attached to the drain.
Open
This is called a direct drain and they are not easy to find compared to tub drains that drain via the overflow pipe. Watco and Dearborn Brass both make kits to do this, available in the US.
Its your bathtub drain.