Ones of the Dragon Skills is named "Polymorph" ... you should really try it out on the flying monsters!!

... Then they're "a mouse for the cat"
If you mean with the "river valley" that Flying Fortress at the end of the Orobas Fjords ?... O no, that's Kali's FF and more difficult than Stone's, Raze's and Keara's FF .
One of the first things I did when I've taken over the Battle Tower was searching for 3 different kind of Zeppelin parts so I go to Aleroth as soon as possible !
There in Aleroth are very good traders (if you like some trading?) : the funny speaking Zarniyar and (the smith) Pilcher. Mercator only sells herbs, foot and drink (I believe).
Zarniyar has very nice things to buy, I visit him each time I level up ...
Zarniyar .... he reminds me of "Hercule Poirot", the 'small Begian detective', or better say : "Le petit Belge'