As far as I know there is no high-beam adjustment. Since the low and high beam filaments are in the same bulb I'd assume that Nissan would have designed the housing and adjustment in order to align both at the same time, but perhaps not...
There is an electrical modification you can do to keep the fog lights on with high beams, but this is more of a workaround since the fog lights really don't go that far. If you're interested in this mod, see
this thread.
HID retrofit "plug-n-play" kits do
not belong in halogen reflector housings. They will scatter light everywhere and cause massive glare for other drivers, plus the typical blue color temperature of the lights will result in even worse visibility in inclement weather even though it may seem brighter. They are also technically illegal according to some DOT specification, if I recall correctly. See
this page for more information regarding why HID conversions are a bad idea.
Furthermore, ensure that your current headlight bulbs are *not* ones with blue coating over the bulbs. The blue coating makes the light output seem brighter, but it is not. See
this page and
this page for more information.
I would suggest polishing your headlight assemblies with Meguiar's PlastX and a microfiber cloth. This will remove a significant amount of cloudiness and yellowness and should increase light output somewhat.