Leisure battery use for tv

Hello all, We've just bought our first motorhome and there are so many questions. We are learning as we go but the leisure battery & appliances we can use confuse me.

We bought a Cello 12v/24v/240v smart tv to install and it has come with 2 power cables. One is to the cigarette lighter socket which obviously will run down the vehicle engine battery, so we won't use that.  The other is to a 3 prong plug via a black box (adapter?).  If we plug into the leisure battery powered sockets when not on electric hook up will the tv be using 12v or 240v?  Will this drain the leisure battery?

The other question is can we just plug our laptops, ipads etc in to charge or do we need something to allow us to do this safely?  I do have an inverter to charge them from the cigaretter lighter as we drive along.

Thanks for any help.