Be calm, take a deep breath . . .
Well start by writing those things down as a checklist so you know you are performing your entire job.
And start doing the stuff . . . like getting a fire code, and taking inventory.
Make sure you set up a written schedule for clean-ups, preferably posted on a big poster so the person's name and responsibility is clearly there . . . Work with your Exec board on this.
If you know people in other Fraternities on campus, call them and ask for the house managers number. Get together and talk to them and see what the pitfalls are, buy them lunch.
Call other chapters, your National website should have a chapter list and phone numbers, and talk to their housing managers.
I would talk to at least 5.
Do you have a housing corp to deal with?
After you have a the big picture in your mind, start working on abudget and the other things you will need.
Oh, go buy a 3 ring notebook so you can write everything you are doing down, contact info etc, and make it journal style in one section so the next poor bastard that gets stuck with your thanless job doesn't have to reinvent the wheel.
You should do fine
Take care.
James