In a single cell mod there's no need to remove the battery to charge.
It's advisable in multi cell mods because most mods aren't generally that good at ballancing the charge between the batteries.
Aye the nano sounds good for how you want to vape. The wasp nano rda or rtas are decent too. Some flat ni80 wire at about 24 awg and some cotton and you'll be flying at about 30w.
Yeah I think I'm gonna go with the tarot nano and then get used to it then get a rebuildable tank in a couple of weeks...I've seen the nanos on eBay for about 35 quid I'm just gonna have a look elsewhere cos eBay's a bit of a minefield.