We usually use this stuff, or something very similar.
Air: It is pretty easy to avoid trapping air, we cut the tip of the silicone tube to the largest diameter, then fill the syringe until it's submerged. The process is straightforward, and we'll be creating some videos to demonstrate.
Speed: Optimal printing speed is somewhere between 15 and 30 mm/min.
Curing time: depends on the formulation (check the manufacturers specs), but typically 24 hours.