I dont thing that it would be of great help but in both my micra (1st facelift and 2nd coilpack) it was just a case of unscrewing with relative ease.
If you have a pair of locking pliers it could make your life easier (just wrap it around the point you want, to avoid scratches on the gear lever).
About the second part if you just want a shorter (with no quick shift) get an angle grinder or a shaw, cut the gear lever to the required length and then use a tap and die set to open threads (I think the original is m10) check first.
Alternatively get from ebay a short shift for a gti-r
I hope this helps a bit