Usually you can limit most of your cutting to behind baseboards and use inspection camera's etc. and not have to do too much damage, but each case is different. 

Installed cameras in front of driveway and in front porch only to find out that he's been in the unit all along.

I don’t have any security cameras on site and would prefer not to have them there long-term but perhaps it makes sense to have a camera short term in case someone damages the drying concrete?

"Ring" doorbells use the hard wiring from previous normal electric doorbells to provide wireless internet connectivity to the built in camera.

There are a lot of great options out there; aside from providing the basics (ie. listing tool to get the property published to 10+ major sites, scheduling tool to schedule viewings, tenant screening with comprehensive applications which include nationwide criminal background checks + credit checks + eviction history, digital lease creation tool, rent collection tool, and maintenance tracking tool), some services also offer your tenants additional capabilities which makes it an easier sell on your end when getting them to transition over (ie. their ability to report on-time rent payments to the credit bureaus; this can create an added incentive for making sure they pay that rent on time).

A lot of investors I know use an app that scans in and keeps business cards digitally.

Buy yourself a circuit tester, a quality flashlight, a sonic tape measure, your cell phone camera and a notebook . . . take notes as you go through for flooring, electrical issues, plumbing, roof, etc. 

They need to create drama for the cameras.  

Here's one example that includes a camera: https://www.amazon.com/AMOCAM-...I found it with a quick google search of "multi unit camera doorbell"

What I have done with my out of state clients is drive through the neighborhood and surrounding blocks with a go pro or a dash camera.