I ride a Langster in NYC. I recently changed to a much smaller gearing from the stock 48/16 to 42/14 (way small, I know. I was too math challenged to figure out that a 44 or 43 chainring allowed for a much more useful range.) However, I'm evening out my pedal stroke, climbing the bridges easier and learning to trackstand. I'm happy to spin and leave the mashing to those mightier than me. My knees and I are friends again.

(edit - I'm actually running 42/16. As others have pointed out 42/16 and 48/16 are the same gear.Though I've got it as 81 inches, not 78.8. But I'm using a chart, not real math.)

Ride the BB 'til it breaks. It will soon enough. Keep in mind you'll want a square-taper 102 or 103mm spindle BB to replace it. If you see a good deal on a good BB, grab it and install at your leisure. By all accounts your rear wheel will give out next. You can easily build/buy a good replacement.
All that remains of my '04 Langster is the frame. I put a steel fork and steel handlebars on. The front end is solid and heavy and rides like a dream. I replaced everything else because it was a long, cold, lonely winter.(Did you know you can buy bike parts online 24hrs a day? Without even getting up? Without even a good reason?) My around town beater is now too nice to lock up.
BTW are you riding the 05 version? I think the tubing was upgraded. Post the specs and any pictures when you get a chance.

Thanks for reading, Mark.