Hmm, not sure if balls grow again. I would think so, but by the time theyve grown again and released their pollen then youll be harvesting by that time! Youll probably get a few seeds when you harvest, but its no biggie. Not like my lowryder where nearly every calyx is seeded... hmm, dont think Im gonna get to smoke any of this one ah well.
The plants look very healthy; dont worry about a few leaves going yellow - Ive had one plant nearly die on me and Ive managed to revive it (God knows how though!). I was thinking that they looked a little stretched, but then I read that youre using a HPS to veg with (ditto). My White Rhino is horribly stretched compared to yours - hopefully now shes grown a bit taller and 'got into the light' she'll start to become more compact. Im not bothered, either way shes being thrown into flowering in a couple of weeks