Insurance
To protect your officers, you will probably want insurance. You may also want to include liability coverage in addition to the coverage that Scouts BSA already provides. Additionally, you may want to cover your camping gear, camping trailer, and other property. Just remember that most policies are for replacement coverage. What is an old tent really worth?
While this list is very helpful to get you started, (it worked for me in Pennsylvania) it does to replace the need for competent legal advice in your jurisdiction.
Insurance & Taxes
Insurance coverage
On this one, I rode the coattails of a gentleman who had set up a non-profit to charter a different Scout Unit. He negotiated insurance coverage to mimic coverage for a PTO at an elementary school. AIM Insurance has treated us well through the process of purchasing this insurance.
990-N Simple Form
Small non-profits with less than $50,000 in income annually can file taxes using the 990-N form. It is an online form referred to as "the postcard" because it is just that simple to complete. The hardest part is logging in.
Tracking Donations
Your donors will probably want a letter from your organization recognizing their tax deductible donation. Tracking these letters to make sure everyone gets one is very important. Here is a letter we have used.