Congratulations on your marriage and your investment in your future.
I am a mortgage broker and real estate investor in Philadelphia and I would like to answer a few of your questions.
-The mortgage you obtain on this duplex will not prevent you from obtaining another mortgage down the road. Your qualification is based on your income, credit and your debt to income ratio. Lenders will look at the total amount of rent you collect on an investment property, minus 30% for expenses and the remainder is counted as income for you. So if your investment property shows an income after subtracting 30% it's counted toward your gross income, if it shows a loss after subtracting the 30% it is counted as debt. Each lender sets the acceptable number of mortgages you can have in your personal name, usually that's 10. if you have questions you can find my contact info on my website at: http://www.liveinphilly.net
- You should be concerned as to whether the duplex is currently rented or not. If it is vacant it is likely that the current owners have had difficulty keeping it rented...and you will inheret their problem. If you feel strongly that you can keep the other unit occupied, run some fake test ads on either craigslist.org or in a classified ad in the local paper. It will give you the opportunity to test the response and proper pricing for the unit.
-If you have no experience managing rental property or renters...I strongly recommend purchasing "Down to Earth Landlording" from author Don Beck. He is a local real estate investor and ace property manager who really knows his stuff.
Good luck to you, and remember that property management, managing renters is a business and carries with it similar risks and rewards. Prepare yourselves and it will be the best thing you have ever done.