ray22... no problem. Glad that you found this thread useful and happy that it saved you a nice chunk of change.
The questions about the bulkheads are pretty easy. The double threaded ones have an internal thread on the internal of the outside the tank piece. You will have to use Teflon tape and a piece of PVC called Male Pipe Thread to Slip . This will allow you to change the plumbing later.
The second type of BulkHead is the more standard Slip fitting. This needs to be solvent glued to a slip fit piece of PVC at the connection making this connection permanant.
Hope this helps some.