Sorry, it looks like your question fell through a bit, despite being relevant and well written.
Hard to say, there is definitely too much code for me to run in my head. Could you share your plot and summaries of the fits (or the underlying data, so that we can run the code for ourselves)?
I am not an expert on metaanalyses, but I don’t think the concept of weight has a direct counterpart in the Bayesian setting, but you might be able to compute something similar - I discussed this a bit at Questions on multilevel meta-analysis with brms - #4 by martinmodrak feel free to ask for clarifications if that part is not clear.
Tough call. I think you could show a separate forest plot for both conditions? Summarising inferences from bigger problems can be tricky, because there is just too much stuff to show…
Best of luck with your model!
P.S. note that you can use triple backticks (```) to mark code blocks - I edited your post for you.