Where to change the master page?   Well, if you don’t have the Publishing feature activated navigate to http://your_server/sites/examples/_Layouts/ChangeSiteMasterPage.aspx   If you do have the Publishing feature enabled you can go to Master Page on the Site Settings page, under Look and Feel category.

Method that returns an existing SPList on a SharePoint web (based on list name) or create a new one if not found. [More]

Method to return true/false if feature exists on SPSite collection. [More]

In order to get the current SPWeb context that the feature was activated on I have used the following extension method. Regardless if the feature is web or site scoped the following GetWeb extension will return the current web context. [More]