Yes, multiple people can be in Cash Receipts Entry at the same time.  Each Deposit Number can only be accessed by one person though.  Each of the users would need to be entering receipts into their own Deposit Number.

I believe I need to have the batch processing check box checked .... correct??

If each of the users wants to print a Cash Receipts Journal and update it separately, yes, you would enable batches for Cash Receipts Entry.  If the users can enter their deposits and then the journal printing and update done at the end of the day (or whenever) for all of those deposits, then no it isn't necessary.

Thanks for all this information...

If you get DSD Multi-Currency I believe you would need to enable batches for this.