WARNING! This is a scam!

I can assure you that it is in no way a scam. I compile a lot of Mac wallets and have never included a virus or tried to scam anybody. I assume you are receiving this message because I am not on Apple's list of trusted developers (obviously). This is normal, you will get this message opening any app you download from the internet that is not from a trusted Apple developer.
No.
When a Mac application is not signed, it is clearly stated.
Here is something else: If you click, the program installs a fucking plugin for Firefox, Safari and all other browsers. This plugin displays advertising on ALL the sites you visit.
To install a Mac software we have to use drag and drop. All Mac wallets works like this (except Nxt and CHACoin -> JAVA). This avoids installing viruses or trojans or any crap plugin...