About Build files generated by Unity

Not sure if this is the right section for such questions, but anyway wanted to ask a few things about builds.

As everyone knows a data folder is created along side the executable, in this data folder there are various files, most improtant ones are the assets but there are some others I don't know if they are really used by the program when running as deleting them didn't bring up any problem.

More specifically I'm refering to the files inside Mono folder, sure mono.dll is required so that I wouldn't touch, but the folder called "etc" has some configs in it that I have no idea what they are for, deleting them has no impact. Same goes for the file app.info.

Last thing wanted to know is if I delete dll inside Managed folder that are not used in the program at all would be a problem. My game add the UnityEngine.Networking.dll assembly in that folder but there is no trace of it used in my game, no name spaces ever used, infact deleting it does no harm but still the Assembly-CSharp has a reference to it (that I can't get rid of in monodevelop or vc#) and I wonder if a referencd assembly that isn't there but not used could cause problems.

Thanks.