If I have a spinal cord injury, what wheelchair transfer techniques are available?

See answer below. It all depends where you need to transfer to. Check out fasteddy07 on youtube where I demonstrate how to perform a variety of wheelchair transfers, on a shower bench, on a bed, in a car, from the floor etc... Of course, depending on the injury level, some transfers may not be possible independently.
Depends. It is based on the level of the injury and residual function. C7 injuries should be able to transfer independently with a slide board. Higher levels may require a lift.