I find it very disturbing to see the vast difference in their values versus our values. I am not overestimating or exaggerating. I am very disturbed by this. And have been for many many years. Even from my first exposure to a French exchange student in 1970. Mopeds? Wow, that was an eye opener. I really don't recommend riding on the roads of this country, for the reason that we are not valued. I've only been forced off the rode one time since 1967 when I started. It does depend on where one is riding. Rural riding is where one faces the morons. City riding one just has to be vigilant. I hope you find what you are looking for. And I really hope it works out. I love to see more people on bikes. You have to look hard to find the eclectic builders, but they do exist.
As for a chain guard, I really don't think you'll find that here. Not in the higher end bike. Breeze bikes do have the chainguard. They seem to have many more years of bike building over in Europe. And they value cycling and cyclists. I'm sorry, I find it hard to not bash America when it comes to biking.
Having said that. I know that Joe Breeze has a company that makes a line of bikes. He's one of the early mountain bikers. I don't think they're cheap. But he does have a line of step through frames.
Giant has a steeply sloping top tube design that might also work. The Ranier model. Or their full-on girl's bike. The Suede.
As for internal shifting mechanisms, Shimano, Rolloff, and another I forget, make them. They are not cheap. But they are really nice.
Here's a couple of the links to the sites I mentioned.
http://www.giantbicycle.com/us/030.000.000/030.000.006.asp?year=2005&model=11083Breeze makes what you are looking for. He made the very first custom mountain bike. I know the guy who owns it. And I doubt they are cheap.
http://www.breezerbikes.com/bikes.cfmThis is the Ranier. I think it's the '06 model.