Use software to automate it.

Just wanted to connect with likeminded investors that are into hotels, casinos, multi family, etc. 

Then hopefully you'll be on cruise control for the next 11 months+ until they move out.Here's a long list of landlord software companies. 

If I were to manage it myself I know that there is software that automates most of the messaging like igms, or yourporter.

You can also buy lists from companies like list source and there are some REI software companies that have a cash buyer search feature.Best way to find motivated sellers is to purchase lists and compile lists from city and county for 60-90-120 days late on mortgage, pre-foreclosure, delinquent taxes, water cutoff, code violation, probate, divorce, high equity, etc. and mail or cold call.Other methods are driving for dollars, door knocking, wholesalers, craigslist, Realtors, FSBO sites, expired listings, foreclosure sites, put out bandit signs, billboards, newspapers, other offline publications.You can use pay per click/adwords, facebook, Linkedin, Youtube, and other forms of online and social media.Bottom line is consistency.

An addon is considered a separate program (software). 

Buildium is probably the cheapest option as far as professional-level software is concerned but that's probably unnecessary at your level. 

Along with some other softwares.

My question for you more experienced folks is how can I go about creating my own MLS system for the country (no legal rules apply here, I have asked), or if there are softwares where I can input data into without creating a software from scratch.

I 've lead technology teams in software development, systems engineering, telecom engineering, and network engineering.