Okay so I move first and ram you
we both take a point
I move back to the next available notch on the maneuver tool
!?! I am at speed '0' until I move that ship again
are we both at speed '0' until we move the ship again or just me? (I think it is just me)
can I use engine tech and a navigate token to turn and move one notch as you are executing a new ship movement and you use the token during step 1 DETERMINE COURSE ???
If you ram someone and your ship is unable to move any notches your speed "temporarily" can be reduced to 0, however it immediately returns to the value set on its speed dial as soon as the ram is resolved. In other words, the speed reduction is just a clerical technicality way of saying you don't actually move as far as your speed says you should.
If you executed a nav command that turn then yes, you may ram a second time and your speed will again be temporarily reduced to 0 until the second maneuver is over.
What Forgottonlore said.
When you ram another ship you temporarilly reduce your speed (without changing the speed dial) and bring your ship back along the movement tool until you can place it, even if it means staying in the original place i.e. you moved at speed 0, then you both take 1 face down damage card. This does not effect your ability to use defense tokens because you do not change the speed dial - as per the instructions in the RRG under overlapping. So when you are defending and you check against your dial, it does not show speed 0, so tokens are good to use.
If you have engine techs and perform a navigate command then yes, you can ram on the original move, come back till you can place the ship, and then perform the additional 1 speed move to ram again. (both ships would then take 1 damage card from each ram, so 2 total each assuming the same ship targeted).