Specifically for an investment property, as a buy-and-hold investor, would it be wise to take out a 5/5 ARM as opposed to a 30 year fixed loan (since it is very difficult to find a 30 year fixed conventional loan even with a 20% down)? 

Opportunities abound, you just have to train your brain to spot them and your arms and legs to execute them ...

@Jacob Price i forgot to explicitly state that the guys stated expenses are laughable but thats what you can sometimes expect.  

What all the MultiFamily lovers forgot is that sub 6% rates is nothing more than a gift, in time their 3% arms is going to be a 6% arm, and one day a 8% arm.

But they only offer me 5 yr arm loan.

As to the deal you're getting, personally, I wouldn't do an ARM yet.  

The loan has a higher than normal interest rate and a 5/1 Arm.

I'm having a hard time explicitly finding this for Burbank. 

Had this been a case where a second mortgage had been issued between to unrelated parties in a value for value arms length transaction, then the bidders who did not do the required due diligence would be out of look.  

This generally limits you to local lending that have slightly higher rates and only offer 1, 3,5,7,10 year arms that reset at the same interval.Doug