Wow, someone will actually be in Baltimore! I live about 15 minutes south. Baltimore can be veg*n friendly. There are many restaurants (Indian, Afghani, Thai, etc.) that you can navigate around. There are also several veg*n specific places like the "One World Cafe" and "Red Emma's". I think there are a few Whole Foods as well - one in Northern Baltimore and one basically downtown.
For food - Mt. Vernon and Federal Hill are good choices - the downtown area known as the inner harbor has many restaurants but mostly chains
There is a bus system but I do not know it too well and also a subway (believe it or not) but have never been on it and it is small. By car, Baltimore is pretty easy to negotiate, if you have access to one.
For entertainment it depends on what you like to do:
For bar scene Federal Hill, Canton, and Fells Point are decent as is Mt. Vernon. However, as I am basically a home body and haven't been part of any scene for MANY years these are just the old standards.
Museums: Walters Art Gallery (Mt. Vernon), the BMA (near Hopkins), the MD Science Center (Inner Harbor), Port Discovery (kids museum, Inner Harbor)
There is theater and the symphony (just dated myself) is great. There is a decent local music scene but I am too old to know much about it and various live performances of more known groups - pier 6, 1st Mariner Arena, Power Plant Live, Merriweather Post Pavilion (near me in Columbia).
They also have various festivals - Fells Point Festival, Hon Festival, Artscape, and a bunch more I'm sure . . .
DC is only 45 minutes away.
Lastly, as I am a soccer fan, this summer in July AC Milan is playing Chelsea in Ravens Stadium and from my perspective, the best usage of the facility!
Enjoy Baltimore and feel free to ask any questions at any time.