On the front preload, the 27mm nut is the fork cap and should be tight. the 17mm adjuster (with only two flats) is the preload adjuster and as you turn it clockwise, fewer lines should show, and the preload is increased.
The screw in the top is the rebound damping, and the one in the lower fork leg is for compression damping. Clockwise increases the amount of damping and you should always count clicks from full one turning counterclockwise. Under the cap, there is a specific setting for how far the preload adjuster is threaded onto damper rod tube, with a lock nuts to hold it in place.
Here's a couple of good reference articles:
http://www.webbikeworld.com/tbird/fork/ (changing fork oil)
http://www.triumphnet.com/st/acc/racetech/setup.htm (setting suspension sag).
I hope this helps.
