1. There are instructions in the Symantec Management Platform Users Guide, "Preparing a Windows 2008 R2/7 computer with IIS 7.0 for use as a task server", that you can use to make sure all required features are installed.
2. The Symantecf Management Agent should show the Task Server installed in its list of plug-ins.
3. When you run the msi to install the Task Server use a command like:
msiexec /i taskserver.msi /l*v "%temp%\taskserver.log"
4. Unless you are using Deployment Solution to deploy images you don't need a Task Server on every site, they don't help with bandwidth, they only offload processing from the Notification Server.