how to get auth keys for ssh via os x onto paperwhite

i really want to be able to sftp into my paperwhite via wifi, so that i can both usb mass storage and access the filesystem as the same time.

a few problems:

1) no password on 5.3 up.

2) i don't know how to set auth keys on/for/with os x.

3) will transmit then work after that?

4) as see by my shenanigans, i'm not entirely clear on
(although i think i am, now)

and

can anyone steer me in the right direction?