As you walk down the slope leaving the cave of Dragon Spire, you come to some tree tops. If you look down, That is still Ishad N'ha. (you can probably still see Torin standing there)... so to get
back to Ishad N'ha you just jump off the ledge on that side of the trees...
...However, unless one of your party has 'create portal' and 'teleport', you will have to plod all the way through to get back to Brimloch...
As far as the clothing goes, I'm the not one to ask. I always try to wear plate or chain. I have worn special garb at times but only in a pinch, when I had no choice....and besides...If it's working for you..
...why change.