I'd say don't bother with the kiddy rides near the observation tower (I forget their names, but there's a couple of boat rides and a couple of small-car-on-track type rides, all outdoors). Most other small dark rides have a certain charm, such as Piccolo Mondo and Bench. The bigger dark rides like Giesterschloss and Pirates in Batavia are must do.
It's not the best park for flat rides, but the spinning planes thingy near the wild mouse is quite fun. Nowhere near as intense as it might look at first, so don't be put off if you're not a spin fan, it's no worse than a Wave Swinger.
The rapids
can be very wet, but they do tone down some of the effects in colder weather. Speaking of wet, Atlantica is actually quite dry, as the wave is thrown forwards and away from the boat... Whereas Poseidon will leave you soaked.
Cassandra (the mad house) may not be the best, but it is certainly "different", and has a great soundtrack.
The brothers Grimm thing in the enchanted woods area is good for a sit down when your feet hurt, but not worth waiting more than a couple of minutes for.
I'm sure more will come to me in 48 hours when I'm there.
As for Project V, I have no idea.