Thanks for the additional details. In order to accomplish #1 you would normally use the "select nodes" feature in the BiNGO output, just like you attempted to do in #2. And, indeed, this feature appears broken! I had to run Cytoscape from the command line to display these hidden errors, and there is in fact a Java NullPointerException being called when that button is clicked (that's why you see nothing happen). I'll file a bug report and cc you on it.
In the meantime, there is a workaround. It's a lot of steps, but only takes minutes:
1. Find the GO terms you want in the BiNGO output table
2. Select all the corresponding "gene" fields (you can use shift or cmd for multi-select)
3. Copy into clipboard using keys (e.g., cmd- or ctrl-C)
4. Paste gene names into new text document (e.g., text edit or wordpad)
5. Add carriage returns after each ID, so that there is only one ID per line
6. Save as go_genes.txt
7. In Cytoscapes menu: Select>Nodes>From ID List File…, choose your go_genes.txt
Voila!