One thing at a time.

Moving tempdb:
Moving SQL Server databases to a new location with Detach/Attach
http://support.microsoft.com/default.aspx?scid=kb;en-us;224071

There is a specific section on moving tempdb.  BTW, the newest
recommendation is to have one file per processor in tempdb, even if they are
on the same spindle set.  This is only for tempdb.  I would do this first.

You can move a table from one filegroup to another by dropping and
recreating the clustered index and specifying a filegroup for the new table.
One alternative is to detach and attach as per the above KB article.  If you
have only a very small maintenance window, then you can do a backup and
restore with norecovery to the new locationso you can apply transaction logs
to "catch up" when you switch over.  Simply rename the old and the new
databases after finishing catching up and you are in business.

You will have to recreate each index on each table independently to move
them to the new filegroup.  You can use the INFORMATION_SCHEMA views to
generate lists and with a little string manipulation you can create the
scripts almost automatically.

As always, test everything on a server you can afford to break.