Nitrogen (the first value in the NPK designation in fertillizers, is what generally promotes vegetative growth, so if you have a moderate amount in whatever you buy, you should be okay. Products like Miracle Gro (the regular 15-30-15) should be fine to give both vines and flowers. The passifloras can get rampant so make sure you have something for their tendrils to attach to.

You could plant morning glories and use fishing line for them to grow up on. That will provide you with some privacy.

You could do as I still do, which is buy a wood trellis paint it any color you like and grow mandevilla or morning glories. I'm going to try and find a photo to show you wat I mean. Now my balcony was black wrought iron, so I painted my wood trellis black and it has lasted for 6 years.