Victor,
I think your Water and Sewer is a bit low. I have a 3 unit property (3 x 3bd, 1 bath) in Bridgeport. I pay just shy of $200 for water and about $250 per quarter for sewer.
For taxes and property information go to: http://gis.vgsi.com/bridgeportct/
While I haven't had any vacancies in my property yet, i think your vacancy rate is a bit low. with two studios, i would expect a bit higher turnover. I used 12% for my property analysis (we are in West End). Think about it, just one month of vacancy for your larger unit will be about 3%. If you have a vacancy that lasts more than a month you are already over your vacancy expense for the year. Maybe someone else can weigh in with their actual vacancy expense for properties in Bridgeport, CT?
Lastly, based on what I'm experiencing.. unless the place you are looking at has been recently renovated, I think that your Maintenance and Capex are low. Unless of course you plan to be your own handyman. If that is the case then you might be ok.
Best of luck! I hope that I was of some help!