some questions

i am looking into opening a hostel in nyc, but i have a few important questions that im hoping someone can answer for me:

I am looking at a building that is 2 floors
each floor is 3600 square feet
so approx 400 sq. meters

for a total of
7200 sf or 800 sq meters

currently the inside of the building is totally an open space
with 16 foot (5meter) high ceilings

i need to know
1. approx how many beds (assume just single, not bunk beds, for the sake of being simple) can i fit in this place? Is there a standard # of sq feet per bed?

2. How many people per toilet and shower is the correct ratio?

ALSO
the building is gas- heated
question:
Any idea of how many THERMS (thermal units) of gas a building 800 sq meters/7200 sq ft would use per month?

FINALLY***
Is there a reccomended or maximum proportion that rent should cost compared to maximum monthly income?
For example, for residential real estate, they say that rent should be around 25% of your income.

I am a bit nervous because the buildg i have seen is $19,000 per month !
The owner will give us the first 3 months free, and for the second 3 months will let us pay only $15,000. But then in the 6th month, the rent goes up to $19,000.

So i am worried that this is too much. Any advice?

Also, the front of the building has amazing retail space in front of a park, so it could be used as a cafe and/ or bar, or i could just use it as part of the hostel (the retail space is included in the 7200 sf/ 800 sq meter)

Thanks so much for all the help!