Karazikars Maw and getting between levels.

I've run into 2 slight issue I'm wondering if anyone knows the answer to.

1) how many bridges are there in total? Do they intersect with each other at all or is it only straight across to a different level and the only way to chance levels is to climb between bridges as it says in the the general features where you can spend 10 feet of movement to climb up to another bridge on another level.

So from that and the rest of general features I'm imagining 5 bridges total from 1-2, 3-4, 5-6, 7-8, 9-10. Basically with the slaves he's got it so all they can do is go from living quarters to working quarters. Does that sound right?

2) It then also says that Karazikar opens up combat by targeting the bridge and trying to drop them.

So if I where to do this that creates a 20 foot gap. How would they get higher. Obviously fly, spider climb, etc is usable but mid fight how would a melee character close that distance? They have the gecko mounts but I'm going to have the guy tell them they can't bring them.

I'm guessing maybe let them climb the walls? Whats the DC and wouldn't the beholder target him on the wall and that could depending on the save type be at disadvantage (like a dex save)