A way to post on other networks that brings the people reading those posts and their feedback back into G+.
The last thing I want is to auto-post a G+ post on Facebook, and trigger an interesting conversation there that I don't participate in. And I don't want to turn G+ into a megaphone where I'm simply talking at people without enabling them to talk back. That's not a conversation.
Reiterating the already made comments above, here is what investors typically value most from greatest to least:
1. Fully functional MVP with paying/profit-inducing users
2. Partial MVP with paying/profit-inducing users
3. Full or partial MVP with real users
4. Full or partial MVP with beta users
5. Full or partial MVP (the real product) with no users
6. Interactive prototype
7. Wireframes and mockups
8. Powerpoint slides
The closer you can get to the top of the list, in general the more motivated an investor will be. Of course, this is real life and you can't just jump to position 1 or 2. For this reason, if you are only at a position 6 to 8, it is often better to focus on pitching technical cofounders first, getting to at least position 5 or higher, and then pitching investors.
You can build an API in any common language. Since you are already comfortable in PHP or Python, your time will be best spent using one of those languages. I'm guessing your client will be expecting the product some time soon. =)
I would recommend structuring it as a RESTful web service though.