a mic, a pickup, and a di box -- questions from an electro-phobe

When I was sixteen I played "Honkey Tonk Woman" on an electric guitar to impress a girl. It didn't work. She liked the bass player. That was the last time I played anything amplified.

In early Sept I will be playing my first gig and I have some questions about how to use a mic, a pickup, and aDI box. (And to be honest, I don't even understand what a DI box is.)

OK, so I bought a really nice used dulcimer from a phenomenal professional player whom you all know. It has an internal pickup. I was told that when I plug in, I should use a pre-amp and decrease the volume on the mids. Iam prepared to do that and bought an LR Baggs Para Acoustic DI.

But none of my other instruments have pickups, and at my gig in a few weeks I'll be playing not only that dulcimer, but a guitar, a baritone dulcimer, and a baritone dulcimette, none of which have pickups. So I've obtaineda Shure SM57 mic to amplify those instruments.

I was told that there would be one line to the mixer for each of the musicians (there are five of us). It seems to me that I would be best off running that line from the DI box and then swapping out inputs between my dulcimer and the mic depending on which instrument I am playing. That way I'll be in total control of the instrument and the signal going to the mixer. I knowthe DI box will work well with the dulcimer, but my question is how it will work with the mic. Can the DI box even handle the signal from a mic? If it can, what kind of adapter should I get to connectthe XLR mic into a 1/4" jack? Should I just skip the DI box and use the mic for everything, even my dulcimer with the internal pickup?

Maybe you can tell from my questions here that I have no idea what I'm doing.