I recently had a tenant family of 5 (3 adults who all signed the contract) move into a property of mine.  I did a background check and called the past landlord who lives out of state.  Landlord gave a good review and the background check showed an eviction filed 5 years ago, but dismissed Credit overall was acceptable.  So far, all is good with this tenant and myself, but they've only been in my place a month now.  I received a call from the previous landlord out of the blue today to pass along some information.  I guess he felt guilty not letting me know everything that went on with him and them when I called him a month ago and he apparently kept my number.  He told me today that he had been asking them to move out of the house for 6 months but had been being too nice and not forcing it.  They frequently were late on rent.  He also said once they moved into my place, they stopped communicating with him and have not returned the keys or made the last month's payment due to him.  Also, his 3 year old and 5 year HVAC systems (2 in homes in AZ sometimes) had both been reported broken at the same time once he got serious trying to get them out.  He called techs out to repair the systems and according to him, the techs refused to work on the property and wouldn't provide a reason.  That's really strange and I'm curious what transpired there to have them deny working on the property.  He called a neighbor to check in on the house and the neighbor noticed the house was full of trash through the windows.  I suggested he get an attorney involved and consider an eviction or look into maybe getting it judged abandoned to see if he can get it back that way.

Now this is all what he has told me.  I have no evidence what did or didn't happen however I can do my best to protect my property.  This unit is a 2 hour drive from my home, but I'm willing to make the drive as this is a nice recently painted home with new tile floors.  I'm not afraid to get an attorney involved as necessary.  A few questions for those with more experience:

1. My contract provides no grace period for late payments.  I found this to be abused in the past.  I used a standard AZ Realtor contract. The rent is considered late if not received by 5PM on the 1st of the month and late fees apply.  No payment on the 1st equals a 5 day notice to "pay or quit" will be mailed out on the 2nd.  If someone continuously pays late, month after month, but within the 10 day window, is there grounds to terminate the contract after a certain number of these events?  (Request the tenant leave or evict if denied)

2. What techniques do you recommend against receiving a partial payment as a stall tactic?  I currently am allowing Zell (and check or money order) but have stipulated I reserve the right to change methods.  The tenant paid the first full month through Zelle.  My understanding is if you accept any amount of payment, even not intentionally, that you implicitly have agreed to the partial payment and you cannot evict the tenant for that month.  So if they send me $500 instead of $2000 on January 1, then I can not send a 5 day notice until February 1.  Is that correct and if so, what are the best techniques to combat this?  It looks like a rent service such as Tenantcolud nay have the ability to reject incomplete payments.

2. I would like to perform quarterly inspections.  Is this a reasonable frequency?  I'd like to do it more often, but don't want it to be considered harassment.

3. I'd greatly appreciate any additional advice on for preparing for this situation.

I have been a long time, small scale landlord for a while and slowly am getting wiser, but generally I've had decent tenants.   I hope these current tenants treat me well and I will be respectful also, but I think there is sufficient reasoning to prepare myself for otherwise.  Thanks!