I am currently doing a lot of work with music for young refugees, and have got a little guitar for the littluns to play. It's called a Kapok and the string length(nut to bridge) is 21 1/2 inches. I want to know whether steel strings are OK, or whether it should be nylon (the neck is already up a bit). And what gauge should I use? I'd like to be in normal tuning for compatibity with other people playing guitars. But if it ought to be tuned higher because it's small, how much higher? Would be very grateful for any advice.