It is a fat binary because it probably supports both armv6 armv7 architecture.
The proper way to install things on ios is through itunes of course.
I am not sure how to install things on mac, without itunes account, as I have never done that, but I imagine jailbreak and using software like CopyTrans Apps should be the answer you are looking for.
As of how to put binary fat into ipa, like I said I have never done that, but maybe just renaming it, the extension will be enough?