How difficult is it for adding extensions Bathrooms/Bedrooms

[Kien Gallwey-Grant]

I'm looking at a duplex property in North Philly and the ground floor footprint is significantly larger than the top floor, so I'm hoping to move the second floor apt kitchen and bathroom adding space for another bedroom. I'm wondering how difficult the permit processing is. Sorry if this is a super novice question, I'm a super novice. 

Thank you,

Kien "Netic"