Updating Splunk instances

quite a lot of questions in one but let's see if i can give a general answer and cover them all:

• How do you upgrade remote forwarders:
  Use a script or a third party tool such as yum to tell the forwarders to grab the new installation file and upgrade splunk to the current version. A simple script that contains wget, tar and some moves and directory changes should suffice.

• Making splunk configuration changes across remote machines should be done by deployment server and client connections. Make sure you make that work, for at least one machine, then use a script to enable it across your domain. Once the connection between server and clients has been confirmed you can add all your config files within an app (or multiple) under the deployment-apps on the Dep-Server, and then reload configs. This should suffice in the clients grabbing the latest config files.

Here are a couple of links to help you out in your quest:
General Idea
Settup Deployment Clients
Define Server Classes

Hope these help,
.gz