Just some ideas of possible guidelines about the new WeAreWikipedia Instagram account.
Access to the Instagram moves through the international wikimedia/wikipedia community like the twitter account. The strength of the twitter account comes from the diverse group of people that curate the account. While I don't think both accounts need to move in tandem, it is a good idea that neither are capitalized by one project or language.
There is no restriction on the type of content as long as it is licenceable under a libre licence and safe for work. I would hate to place the future of the account in a narrow. That being said, good content would probability be things like events, illustrations for articles, topics to work on, and selfies while editing.
All content must be under the Creative Commons Attribution-ShareAlike 3.0 licence. I have no strong preference on the actual licence but the photos need to be able to be commons-able and a single licence makes moving things over so much easier.