Wakobato was operating in September, and you can bring all your stuff on that and Wurmling Express.
FLY front row queue is probably about an additional 45-60 minutes, depending on the length of the regular queue. I would say it's fully worth it for FLY, the front row is much better than the rest of the rows. You feel like Harry Potter.
I got absolutely drenched on Chiapas, like "I just took a long shower, fully clothed" wet. I got off River Quest almost entirely dry, though I have heard the reverse, so your mileage may vary. For Chiapas, try to keep your feet up off the floor if possible, as water gets stuck there and sloshes back and forth and will absolutely soak your shoes.
The front row for Taron says "45 minutes from this point" at the queue split, but when I went, on an admittedly light crowd day, it was about an additional 10 minutes for the first row. You can look at how many people are in that line, assume one minute per every pair (I timed this and it was very consistent), and do the math yourself. Also can wholeheartedly recommend waiting for this, Taron front row left seat is probably my favorite seat on any coaster I've ever been on.
Some of the rides in the Berlin area open earlier than 10, the carousel and swings I believe.
And finally, there's a lot of various snack food in the walking path between the end of Berlin and Mexico. The vegetarian pizza was good, the frozen yogurt was good, and I had a delicious fruit bowl as well. Can't speak to actual meals but all of the snacks I had at Phantasialand were great.
Enjoy, it's really a world class park.