抜けて comes most likely from verb 抜ける (to escape,to come out), which is a verb from class that includes only -る ending verbs. (though not all -る ending verbs belong to this group). I'm not really sure what this group is called in japanese.
In this case it is as simple as dropping る and inserting て.
For the rest of the questions, while I have some idea I'm not sure enough.
ゆく could be alternative way to write いく as in 行く.
Note, it could be.