A mutated human consciousness can navigate by instinct. You put the EMH as pilot in that ship and he's fucked and lost. Federation tech has no instrumentality that will work in transspace, and their first job on this project is to stop the mutation that allows for instinctual navigation. The transwarp conduits may be Faraday cages that stop each individual Borg's subconscious (if any might surface) from cause those specific Borg exiting transspace arbitrarily at whim to anywhere in the universe. What happens when you have multiple consiousness trying to direct the ship/shuttle? Does that mean that the pilot has to have the strongest conciousness? How can you maintain regulation, quality control and consistency? How you exceed infinite speed is simple, instead of going so fast you're travelling at infinite space and achieve completely different physical properties, you punch a whole in the universe through to where those properties are normal and you just "are" travelling at infinite speed. Transwarp space. That's how the Borg do it. In Threshold, they actually accellerated till they got to warp ten which was only possible becuase they discovered a new type of Dylithium which rewrote the rule books. Meanwhile the Voth do not use conduits, and they don't seem to need to have a massive run up to get to warp ten.