How to take partitions or filegroups out of service
I can't give you an answer to question 1).
But to answer question 2):
What you are requesting is known as the "sliding window scenario".
If you want to eliminate a partition containing data that is no longer needed you have to perform following steps:


Create a table on the same filegroup as the partition you want to delete (typically, this table is referred to as a staging table).
This table has to have exact the same structure as the partitioned table, including indexes.
Switch the partition to the staging table
You have to remove the reference to the filegroup from the partition function vie MERGE RANGE ...
Now you can truncate the staging table and drop it. What is left is an empty filegroup you can remove, too.


Some more details on this at http://technet.microsoft.com/en-us/library/aa964122.aspx and the white paper on partitioning, available under http://msdn.microsoft.com/en-us/library/dd578580%28v=sql.100%29.aspx.