I do not know what is the tree with yellow flowers. Could it be a Tabebuia? Anyway, the trumpet-shaped flowers are beautiful.
The 4th photo showed the split-fruit of the Gardenia tubifera, where the unripe green fruit was shown in the same photo towards the top right-hand side.
There were 3 yellow plants in the 5th photo. In the foreground, there was the fine needle-like leaved Melaleuca bracteata 'Revolution Gold' on the left and the big-leaved Pisonia alba on the right. Towards the center looked like the yellow-flower but green-leaved Cassia surattensis.