Depends on the dress. If it's a casual dress that is not short, doesn't expose a lot of skin, then that's great. It shows that you really wanted to look special and make the evening or night seem special. If it's a short skirt, shows cleavage, etc. then that's like showing that you are not the relationship-type of girl.
No, dresses do not make a girl look easy. It really just depends on the dress. On first dates, casual dresses are a must :) I always like to wear dresses. It also depends on where you're going for your first date. If it is at a carnival, then it is probably not a good idea. You have to be at the right place at the right time for a dress. Going to a fancy or even casual restaurant while wearing a dress is totally appropriate :)
Looking easy depends on the dress. Casual is better sometimes.
No, not at all. Whether it's the right choice or not depends on what you're doing or where you're going, though. The last first date I was on was at a restaurant, so a pretty summer dress was appropriate. If we were going on a hike instead or something, then no. Anyway, a dress doesn't make you look easy. Assuming it's not super tight and revealing.