Stihl pole saw questions

I have a Stihl pole saw (KM). I have not used it much until recently and the chain is going to need to be sharpened soon. It's a 3/8 chain. The young man at the local hardware store/Stihl dealer handed me a set of files that are labeled for 3/8 chain (13/64.) My reading indicates that 13/64 is the right file but some recommend a 7/32. Since I actually now have the 13/64 I'd like to use them. Is this the correct file?

Second question. Same saw. Is the oil tank on the pole unit suppose to be up or down when holding the power head in the normal position? Seems like the oil tank ought to be on top. There is only one way to connect the pole to the power head. I'm thinking the Stihl store might have assembled the pole assembly incorrectly when we bought it.
This also puts the little branch hook on the top side where it really doesn't have any practical use, as far as I can see.

Looks like all I have to do is loosen the clamp that holds the pruner to it's pole and swivel it around 180 degrees. Or maybe pull it off, then rotate and reinstall?

Thanks!

Well, what I did was grab a Kombi pole pruner off the rack in the store and pointed at the data printed right there on the side of the unit. It said "3/8 P." I even asked him about the P. He only said "this is the one you want." I've never dealt with a Picco. I was counting on him to know what I needed. No big deal. I'll take it back and swap it.
Thanks!

I won't argue about the training, but he is a very nice teen age boy, holding down the fort by himself on Sunday right after church. I'll point out to the bossman, when I return the files, that this could be a teachable moment for the boy. No real harm done except the store is 20 miles away in a little town where we go to church.