I'd look up workshops in your area (maybe offered thru adult continuing ed. or local community art centers, etc.) and see what's included in their listings. This seems to cover a lot of equipment but doesn't describe what the workshop will cover - what will participants be doing for three hours?
I'd look at the pricing too for future reference; this seems low compared to costs in my area for a half day workshop. Usually in my experience there isn't a deposit, the total is paid when registering.
I've found doing presentations that it's necessary to know the information well enough to not have to do more than take a glance here and there at my notes. (Have you ever done any sort of presentation or workshop before?). Your other thread wasn't specific that I read so I don't know if you have figured out yet what information will be covered. I've also found that what I have to cover seems like it will take some time but it goes much faster than I'd think. Of course this seems like it will mostly be hands on with you going around assisting them in setting up and taking photos.
Workshops and classes often give prerequisites - what do participants need to know or be able to do to take this workshop? With this I'd think they'd need to know basics of how their cameras function, like to know how to set the ISO, aperture, and shutter speed etc. on their cameras even if it's at a beginner level.
In your other thread you'd mentioned insurance and the photo titled 'precarious' made me think that obviously if a photographer takes any risks in getting a picture that's up to the person but it's a different situation if you're leading a group. I might not want to use a photo that implies they may be doing anything risky; some people may think it sounds exciting or challenging but if anyone gets injured in a fall obviously it will probably be your responsibility/liability.
I used to be a director of a summer camp program and that's obviously a different level of safety working with kids but I'd suggest you have in mind what to do in case of emergency. (I always had to have first aid training and luckily didn't have to put it to use much.)
I'd think about suggesting appropriate attire and/or any personal gear to wear or bring (such as no flip flops, etc.). I'm thinking it might help you be covered so if someone shows up totally unprepared you'd have something to fall back on (to remind them what information was provided and what is required to participate). It probably won't happen but I'd personally send someone home and refund money rather than put the person or myself at risk because someone showed up unprepared for hiking outdoors.