I worked with spry 80 year olds. You do need to be able to walk some distance over broken surfaces and carry maybe 20 pounds. If you can do that, you can make it. Indeed, they’ve had many volunteers in their 90s.
Tel Aviv is very safe. A fair number of well armed cops and IDF on their days off. M4s in Jews’ hands on many streets keep everyone honest.
IDF bases are very safe. Lots of well armed folks can defend each base unless overrun by a large trained committed force.
In Jerusalem, ya gotta watch your 6, and keep your situational awareness on overdrive. For example, I got purposefully followed by an older (70?) Jewish looking dude, across about 4 blocks, halting and forcing him to go past me, he’d pick up the tail again, etc. Finally, I stopped dead in the middle of of a block and stared him down, hollered at him, forced him to keep walking until he was out of sight, and then I took a whole new direction. He knew I knew he knew I knew. Creep. Had my tactical pen at the ready the whole time. Old City Jerusalem is an armed camp, and the IDF, Border Patrol, and various police are everywhere. Kinda spooky nonetheless.
At this point, a bunch of us are lightly connected around many parts of the IDF. Word among Sar-El-Niks is that it is usual for the team commander to lead from the front literally, and that the man killed was the leader and first through the door.
This is third or fourth hand information here, but generally believed by the group.