It sounds like you are faced with a security guard who has skipped the "wanna be cop" phase, going straight to wanna be judicial officer. Unless...

What happens if I own a building on property owned by someone else and my lease expires?

Very probably. Did you purchase the business from another party? What makes you think you own the building? The original lease should have covered...

Can my apartment complex manager say my brother is not allowed here?

Yes, they can. And you and brother may be able to change their mind by going together to visit managers, apologizing, and requesting they...

I refused to pay for a late fee since I know by law you have 3 day grace period and as well I did not not the 3 day notice ...

Sorry, there is no such law. And there is no such thing as a grace period, though many tenants think so. The issues of late fees is different....

You've got a tough situation. First thing I would do is get an anti-harassment order against this fellow, as that will short-circuit the eviction...

On month to month can a landlord say that resident must occupy the premises for min. 12 months, otherwise deposit is forfeited?

I would say no, because doing so violates the rules about security deposits. The landlord requirement conflicts with the statute, and is therefore...

Tenant relations?

No - you have no right to demand anything under these circumstances. If you really want to turn things around, drop the idea of "demand" and think...

How long does a landlord have to return security deposit on a commercial lease?

If the lease does not specify a review and return period, then the answer is "a reasonable time." I think you are past that point. Write a cheerful...

When and how to give/receive notice?

Your best option may be to do absolutely nothing. Landlord must give you a written 60-day notice to move out. A text is not a notice. So the longer...

If landlord has given a tenant on a month to month lease a 60 day notice to vacate, is the tenant free to leave at any time?

You are technically correct, tenant should have immediately given you a written 30 day notice. But I suggest you consider your best interests,...