Are there any sources out there on a guidelines how to implement a new feature for web or mobile app from start to finish? I'm looking for how the idea is presented to the team and how the managers, designers, and developers should work together. Specifically in smaller teams, say around 5. Something along the lines of when to involve specific members of the team to understand the problem or new feature required, brainstorming, initial designs and potential solutions, and implementation.
Like CodeGnome said have a look at Scrum. Having worked in multiple different teams using Scrum I can totally say this is a good idea.
I just finished Jeff Sutherlands latest book Scrum The Art of Doing Twice The Work In Half the Time and I think its a nice read. Giving good practical insights why Scrum works and how to sell it :).
Read this free eBook over how Scrum could be implemented in a real world example: http://www.infoq.com/minibooks/scrum-xp-from-the-trenches-2