Guys, as someone who has never been to Mumbai, but curious, can you answer some beginner questions for me ( and my g/f)?

Is there no train service that one can take around the city? I see you guys talk of hiring private cars and such, but is there no public transport?

Can you be safe walking around the city at sunset/night? Is it like many big cities in the world, where, if you watch your surroundings, and be cautious, youll be okay, or should you just be best sticking to a driver at night? For that matter, is it safe walking around the city in the daytime?

I guess Mumbai isnt the most how shall I say, "sanitary" place ( from what Ive been reading anyway), so what precautions do you guys take to make sure you dont get sick?

What are your rules for dining in restaurants? Do you only go into places that come recommended or do/can/should you wing it?

Do you guys know of any good travel narratives that I can read about someones experience in Mumbai?

Oh, and one last ( albeit somewhat embarrasing) question on behalf of my g/f: What is the situation when it comes to creepy crawly, multiple legged creatures and rats? I suspect that since its a tropical climate in the 3rd world, there will be rats and cockroaches in abundance, but then again New York City is crawling with those same things.

I hope to share my own Mumbai experiences with you guys one day.

Thanks, and I hope my questions werent too uncouth.