Well, it depends on how you view the SEO world. If by adding the maps to your pages some people begin using them and so traffic is generated for your page, they could be nice but from SEO perspectives they will not help.
Well, I guess not. But it can negatively impact SEO as its a javascript being served from a external source which increases pageload time.
Not for a normal content. But if someone searches for an address, ur result might pop higher. If your website is about travel etc, its always a good idea to have it (even if it has no additional SEO benefits).