Eight hours should be enough for your plants. Technically, I believe that falls under the "full sun" classification. If the vines are producing flower buds, that means they are happy. Score one for you!

In my experience, the first year passis put most of their energy into developing large root systems, and the following year they explode with vegetative growth. I'd recommend you enjoy the flowers, and if you want to encourage more green growth, give 'em an extra shot of nitrogen which will encourage vegetative growth while discouraging flowering.

Awesome, thanks!

I will enjoy the flowers (one opened up on the caerulea yesterday, smells faintly of cinnamon), I even hand pollinated it, maybe I'll get a fruit or two.

I also have 3 incarnata started from seed that are growing very slowly, so I'm really excited about my Passiflora this year.