Here is our first attempt at codifying a guide for style, development, and testing of EVM-smart contracts at Coinbase. https://github.com/coinbase/solidity-style-guide

Our goal is to build the best Solidity organization in the world and documentation like this is an important start :)

meh how do you inevitably deal with external integrations that don't want to use a pinned solidity version

I think that's fine. 

I just dislike the all too common practice of writing them for every contract in your project and inheriting. I think you should he inheriting as few interfaces as possible.

If anything it would be better to autogen the interfaces from the contracts so they can be used externally