Yeah, there's an entire protocol already created around facilitated rec climbs, first by Peter Jenkins/TCI in Atlanta and also used by Tim Kovar/Tree Climbing Planet and an association of rec instructors and facilitators GOTC as mentioned. To southsoundtree's point about lowerable DdRT systems, there is an established rescue protocol that doesn't require that a DdRT system be lowerable, it's not practical to have base anchored settings for a group climb with say 6-8 rope stations (this is common), the rope spaghetti would be overwhelming. You want to have one rope set at a high point that is your dedicated rescue system. Rescue typically consists of talking people thru anxiety or some minor difficulty from the ground, different set of problems/mindset then working climber rescue scenarios.
As far as how high you hang ropes... as high as you hang them people will climb to the top, you just want your rescue rope higher. I frequently have climbers go to 60' or more on a single pitch setting. Height of the rope set is primarily a time regulator, if you want people to be on rope no longer than a half hour don't set your ropes higher than 30'. If you want them to have a deeper/longer experience, give them a high setting. There's more to it as well, check out all the links and names referenced.
Limb walking more than a few feet off the rope's plumb line is risky for novices in a group climb, you can't protect them from swing back from your position running the climb on the ground. If you're facilitating one-on-one up in the tree with them, yeah you could take them on a limb walk.
Consider taking a rec facilitator course, as an arborist you can modify/enhance your facilitating approach after you learn what many others have learned doing this for 30 years or so. Also recommend contacting Paul McCathie, Isle of Wight, UK, he's a Kiwi expat arborist who launched a very successful facilitating/instruction business, his perspective is useful for the working arborist considering a rec climbing business launch:
https://www.goodleaf.co.uk/treeclimbinginstructor/
-AJ