One flux for all electric soldering?
Rosin fluxes work with pretty much everything you named except for aluminum and steel.

Do NOT use the same flux and solder you would use on water pipes.
Those fluxes are acid based, and will corrode your connections.  If you don't clean all of the flux off afterwards, it will continue eating the contacts and at some point things will fail. It may well eat away the solder pad completely while you are soldering.  PC boards use a very thin copper layer, and are created by etching away everything but the traces you want.  Etching is done with acids, acid flux is a Bad Thing.

And trust me, you will not get rid of all of the acid flux.  It doesn't take much to eat away the thin copper of a solder pad.