Is Wikimedia Foundation Inc a registered non-profit?
Yes. See Wikimedia:Deductibility of donations.
Does the Foundation have tax-exempt status in the US?
See Wikimedia:Deductibility of donations.
What is the percentage of overheads?
---> (todo) not yet
Does the Foundation have a non-discriminatory clause in its charter? (should not discriminate based on religion, ethnic background ).
---> (todo) not yet
Is the Foundation involved in political lobbying or have any political/religious inclinations etc.
---> (todo) no
Does the Foundation do regranting (ie., do they in divert grants to other organizations).
No.
Is the Foundation a publicly supported organization? (ie., is it not dependent on one individual or organization for the bulk of its funding?)
Last fundraising report (currently ongoing) : Wikimedia:Fund drives/2005/Q4.
Other sources of income varies, it may come from sponsors, grants or prizes (link).
We value a diversity of sources as keeping independant is the best way to insure our content will stay unbiaised.