If roof needs to be replaced, I call the roofer I trust and replace the roof. 90% of my tenants renew their lease every year.

I have all the payments, maintenance requests, and lease renewals go through the site.

Regarding inspections, some PMCs will be at all, some will only be at the ones that have a high risk of failure or a problem tenant (renewal inspections).These are all questions you should ask when interviewing PMCs.Encourage you to learn from the mistakes of others - by reading posts here on BiggerPockets about owners not having their expectations met by their current Property Management Company.

Is there anything I should know before I just don't offer renewal of the lease? 

They told me that the contract auto renewal by itself without sending me any any notification or email consent.

If you are paying someone to lease the property (even if you self manage), common finders fee is 1 month rent for new leases and 1/2 month rent for renewal.  

The lease (with the current college students) was just renewed through their 2025 school year.I'm trying to figure out how to make this happen with little-to-no money down, as I have other 'irons in the fire' at the moment.I'm planning to offer $400-450k for the home, and am trying to structure something where a conventional lender would loan an amount that would be covered by the current rental rate (lets just say $300-350k)...   ...then, anything outside of that amount, would be carried by the Seller (for a short while)...   ...Seller financed with a ballon in 5-years?  

My arbitrage tenants didn't renew their lease this year.

I communicated with them, shared what the plan was going to be when we renewed their lease, and wanted to ensure that they knew how much I appreciated their long term tenancy in the property. 

A growing number of insurance companies won't do this anymore and will only add a PMC as, "additional interest", which only alerts them if the policy is cancelled or needs renewal.