Hi Shelley,
Though I haven't done the particular walk you mentioned, it gave me reason to
Google the track notes out of interest and I am glad you have decided not to
tackle it as your first Tasmanian wilderness walk. Hopefully you will get there
one day, possibly accompanied by some experienced walkers or after you have
gained some more experience yourselves.
When you asked what a cairn was, that says don't go on this particular walk.
Generically, just to get your head around what some of these more demanding walks in the
Tasmanian wilderness can be like, by way of example in summer it can
range anywhere from oppressive heat to snowing. Sometimes all in the same day.
I recollect on one walk I took it went from fine to snowing on Christmas Day
and I am talking hypothermic cold where you need to be able to pull
a down jacket and ski pants out of your pack and don them and then navigate
through very low visibility. Other times of the year you
can anticipate deluges of rain. Where the track notes mention button grass
bog, in some of these in Tassie, when it gets wet, y
ou can find yourself knee
deep or even groin deep in mud. It can suck your walking boots off. You
find yourself trying to hop between button grass tufts. On the leeward side
of mountains there can be dense forests with fallen trees covered in moss
which you can find yourself battling to climb up and slide over in the pouring rain
and then once on the side of the mountain, find yourself clambering over giant
slippery boulders trying to look out for that next elusive cairn.
The more popular walks tend to have tracks that are largely self evident and
better marked. But even on these, anticipate that the weather can very rapidly change,
so make sure you pack for a broad range of contingencies.
What ever you end up doing, despite it being a small state on the map, keep in mind it usually takes
longer than you think either by road or by walking to get where you want to
go and back compared to equivalent "as the crow flies" distances on the mainland.
I remember when I first went down in the '70's, a Mobil road map of the state still had
some areas of the southwest marked as "These areas still largely unexplored".
but it is finally DONE and Thursday should tell me for sure whether I know what I've been rambling on about or not 
Every recollection by every person who had walked the North East Ridge and got to Pandani described the journey as pretty perilous. Only signed by bright coloured flags and cairns (which I have no idea what they are!), not to mention phrases like "battling through head high scrub", "take a right at the sinkhole" and "I made sure I kept a strong footing while ascending the steep hill as I still have a lump on my leg from 10yrs ago when I fell 10m and hit my leg on a fallen tree" had me pretty concerned about even attempting this.
We would definitely go with experienced hikers, otherwise I doubt we'd make it out alive LOL. One day... 
