A bit of background about it. 

We did a complete background check.

through some research, I found that rezoning a property in Philadelphia is time-consuming and costly so we hesitate.For some background, we are looking within few miles of zip code 19147 (within 20 minute walk), budget under $700k, quadplex preferable or potential for a quadplex, will put 20% down. 

I will definitely do a background check and vet them regardless.

I've been using Google Drive/ Spreadsheets for a while and tend to lose track of things.I just want to have reminders, background info, kind of like rolodex with notes.

Run a credit and background check and verify employment / earnings to make sure the tenant can afford the home. 

I don't have any background in real estate but found out about BiggerPockets a month ago from a friend and have been hooked ever since.  

Don't know much as to your level of experience and quality of deal but if its a screaming deal and you know it is then get it under contract but hard to say without your background.

My background is in finance and accounting, so I have a fairly structured, organized, budgeting mind.

While doing so, I would underwrite deals in those markets and call the brokers to let them know your background and that you are learning/ looking for deals in that market and build relationships so when a deal does come forward then you can make offers.