Thank you all for the replies, especially about the comment on the Ninja! My confidence on the bike, and using it for commuting, rose. I'll get a front brake for it (anybody got a recommendation?) and maybe a rack at some point.

My commute is shorter than 10 miles; in fact, most of the places I'm planning to go to are a couple KMs far. My other main concern was about the wheels, being different and all that, but I guess they'll withstand a regular street with a few bumps and holes, right?