SharePoint Hosted -Great if your SDK only requires client-side code, but be careful not to violate SharePoint Permissions-Asynchronous Processing not really possibleAuto-Hosted -Good Option if On-Premises is completely out of the question.-Asynchronous processing is difficult.Provider-Hosted-Gives full range of possibilities-Asynchronous processing is possible, again being careful not to violate SharePoint permissions
Host web is a givenFeatures include missing list settings
Discuss Search Concepts. Display templates -> Result Types
Javascript is MSFT internal only.Therefore, expect it to change without notice.