Someone with actual authority will come along to answer, but I can at least relate what I've been told and what I've been doing the last few months.
The Alliance is going to ask for a year end accounting of donations. So start getting that together now. Because of the rather small amounts we're talking about, the filing with the IRS is likely to just be a card saying the HEMA Alliance is below the lower limit. Technically, the Alliance is supposed to issue a receipt if the gift is worth over $75; individual filers only need a receipt if the gift is over $250. There's a plan to have an automated receipt request on the main Alliance page, so that takes care of the receipt issue.
The EIN# is needed (along with proper authorization) if a member club plans to open a bank account as an affiliate of the Alliance. This can have several advantages over a normal business account, depending on the bank. The same goes for opening a non-profit paypal account. It means the Alliance Board of Directors needs access to the accounts and should receive copies of the year end statements.
The EIN# is also needed if your group plans on applying for any sort of grant or matching donations. I know many companies still match employee donations to non-profit groups; schools, libraries and charity groups benefit from this all the time and I see no reason the Alliance can't as well. It does make for some more paperwork for the GC and Board.
We're currently waiting for a check to be cut on a $1K grant