the first question: when some one suddenly appears we say: ((Saro kalash dobare peyda shod)) in persian....it means: here, he/she comes again....in the sentence that u said it means the fox showed up or appeard
second question: آهکشان means to whine
پای بساط لنگ is an old idiom for sure that as an iranian i dnt know and use it also!...lol...we dont even study it in our literature!