The majority of my students take an hour's guitar lesson each week, with a few taking fortnightly lessons. It is completely up to you how often you would like to hold our guitar lessons.
I haven’t yet come across a student that does not have some sort of musical ability. Everyone has his or her strengths; some are better at reading notes, some at chords, some at improvising etc. I believe that talent isn’t necessary, it isn’t how talented you are, but whether you are diligent, determined and how much you play your instrument. I've also noticed that a good student keeps a healthy dose of music on their platter.
Yes, lots of my students are children and I'm happy to teach them at any age. I find half hour lessons are best with young children at first as their attention span doesn't usually stretch to an hour.
For the best results I would recommend a lesson every week. This has to be combined with practice in your own time though.