First off, it's just katana- katana sword is kinda redundant. Secondly, if you bought a "real Japanese sword from Japan", it'd cost you more than the average car. If you are like most of us Western practitioners, you're going to have to settle for Bugei or Cheness. A "good sword" depends on your body type, what you use it for, and how often.
The curve you refer to is called the "sori", and for beginners, you wanna get as close to zero as you can possibly get. Less curve=easier draw. After a few years of training go ahead and venture into curvier swords, but it's really a matter of personal taste. The "symbols" you are referring to are called "mei" or signature. In most cases, the company stamps their logo on sword, or as you said before "made in china". Trust me, if it is actually signed by a swordsmith, you can't afford it! Not only that, but there's a good chance it's actually a "genmei" or a fake. Again, this is something you shouldn't worry about until you are really into swords and you're rich.
Lastly, select a sword that you can comfortably yield. Bugei makes great swords, but as a woman they are too darn heavy for me. In fact, I think they are too darn heavy for most people. My favorite sword of mine is a Last Legend model which unfortunately they don't make anymore. I also have a Cheness Tori and Practical Plus iaito. The tori is now my sword of choice because it's lighter than my LL and I have arthritis now. My iaito is decent, and while not the best thing on the market, it is pretty much all any beginner needs. And at $200, it's a decent quality sword. For an iaito, you can't ask for more.
I wanted to add that nihonzashi makes gorgeous and functional swords, but be prepared to drop a couple month's rent on one.