I play mainly acoustic guitar and concertinas. I use a Fylde Magician, and have two identical models - one tuned as standard and one tuned to < D A D F# A D > an open D chord - sheer luxury! This came about when I started playing more and more songs in that tuning and didn't want to confront the audience with the hassle of endless retuning. I wanted to play songs in the order I decided, and not be swayed by whichever tuning the guitar was in. You can see the Magician and the rest of the range at
At present I use Elixer Polyweb strings in Light gauge (12 to 53 thou). They're great if you've got sweaty fingers because they take a lot longer to go dull than conventional strings.
When it comes to amplifying through a PA system I don't like transducer pickups because the sound isn't natural. It's usually too bright and doesn't sound like an acoustic guitar - more like an electro/acoustic. So, I either use an external mic such as a Shure SM57 / 58, or the fitted mic inside the guitar. It's a Tandy lapel mic - very cheap and very good.
I've also got a Telecaster and an Ibanez Jazz guitar playing through a Fender Vibro Champ amplifier, but I use them for recording, not playing at concerts. Same applies to the mandolin, a Gremlin model, but I sometimes take my Framus banjo on bookings. Nice to have different colours for the accompaniment.
I've got a Wheatstone treble #34120 made in 1936, and a Wheatstone contra-bass #29699 built in 1923, both with the English fingering system. There are also the Anglo and the Duet systems and all three are radically different, although to the casual observer they seem to look similar. The English system has the same note playing whether the bellows are moving in or out (as in the Duet system) and crosses from the left side to the right side to play consecutive notes in a scale (unlike the other two).