It will adhere to PVC but cannot be used as a way to join the pipe and fittings. Yes it can be removed after dried.
Yes it does not dry hard. It will take some effort though to get it out as it does with any plug that has been caulked out but it should come out undamaged
Unfortunately it cannot.
No. In that case you would use either STAINFREE Plumbers Putty or 100% Silicone if the plastic is ABS or acrylic.
To seal, yes. Other means is required to restrain ("attach") the strainer.
Drain systems should not require caulk or putty as all components are pressure seals (nylon and rubber gaskets). In most cases the flange for the drain should seat against the sink and the the rubber gasket backed with a nylon washer is secured water tight with the jamb nut. If your drain is leaking from the flange it is usually because the rubber gasket has failed or the jamb nut isn't tightened down. If it's leaking from the copper threads of the drain body you can use thread tape to fix that. If you decide to use a sealant under the flange it should be 100% silicone, which can be submerged once dry. Hope this helps.