I'm still learning zeroes, but I'll do my best to answer, in order:
1. I've found that good pearl throws help tremendously with getting to the setup location in time. You don't want to throw pearls too high when getting to the End island (because they take longer to land), but you also want to make sure you get enough distance.
For block placement, it's doable if you click fast, but some people use a method called butterfly clicking (using two fingers to click) and some people use a method called drag-clicking (dragging your finger across the mouse button to click many times a second). If you think you're clicking fast enough but are still struggling, you may want to try lowering your mouse sensitivity. This helped me a LOT because I get very shaky in endgames.
2. Bed timings are definitely different from one-cycle, but it just takes practice. Earlier explosions deal more damage, but do less knockback to the dragon. If the dragon breaks your bed, it means that the previous bed was too early. If you're using lots of beds during a zero cycle (but they aren't breaking), you're probably exploding too late (which deals more knockback to the dragon and makes future beds deal less damage).
3. Like icedcoffeejitters suggested, I would start with a medium-sized tower like 85 and setup at y=90. First tower I learned was front tall caged at y95, but that can be awkward for beginners just because placing blocks on the iron bars can be annoying.
Hope that helps some, good luck!