I would stick to your file as first you would have to compare both engines hardware-wise to tell if you can use different file as a base. In fact it would not be that hard to define all maps for stage 1 on yours file using any well defined file...

ARX has the same hardware as AUQ engine
so yes you can load AUQ file into your ecu. but remember that crossflashing are not reccomended and there is a chance to brick your ecu

NO, the xdf is for that software version only for that engine code only. addresses are different between files, some are close and can be used as reference to make your own xdf based off a decently defined one. if your car is wideband o2 take your pick from many of the mk4 variant files aww awp, aum, awv, auq etc. find the correct xdf for the file of your choice and start from there. you need to know the immo version of your car so you can pick the correct file. if you flash a immo 2 ecu with a immo 3 filethe car will shutdown on immo. best thing to do is read out the orig file of your car and post it. most members will not even help you unless you follow the rules in the stickies.

I thought the ARX engine was conventional cable throttle?