One point you guys seem to miss, though.
The transwarp beaming device can fit inside of a duffle bag...
...HOOK THAT THING UP TO A STARSHIP! Transwarp beam a starship! BAM! Instant-travel through space.
For what it's worth, the old FASA manuals said transwarp is a combination of warp and transporter systems - beaming a warp field ahead of the ship, or something like that.