Since the old times, even before cellphone camera/video capability, I have been taking digital pics and providing a record to our Clients at takeover and every interim inspection, as well as when special, or unique projects come up...plumbing or otherwise.My practice has always been to systematically walk the property, so the pics generally tell an understandable story.

Technology is only advancing and a digital currency makes total sense.

. — I plan to install a ring camera over the area but does anyone have a gate lock style or brand that they recommend to really secure the property?

Put cameras up in the place so you can record what people are saying as they tour the place. 

I'm about to become a first-time landlord and want to have exterior security cameras at my unit that upload to the cloud.

I think I can purchase about 5-6 cameras to monitor the entire property so it’s not a major operation.

If done right this will save you a lot of time.2) Hostfully: Create a digital guidebook your guests can access at anytime.

I would have someone help you furnish/design (unless you are good at that)  and get professional pics - also get ring door/security cameras - smart lock - nest theromstat - Find a way to make your property unique or stand out somehow.

Has anyone in the Boston area installed security cameras at their property?   

Respectfully disagree, in most states there are usury laws that do not allow you to charge double digits.