True.
You're thinking about a vinylic proton.
Not true. The resulting conjugate base is negatively charged.
You're absolutely right! I don't know what I was thinking!!!
I believe the acetylenic proton is more acidic. Look at the conjugate bases.
1. While the allyl-anion is slightly more stable than an alkyl anion (since the negative charge can resonate throughout the conjugated system), formation of the allyl-anion is not particularly favorable because carbon, in general, is not very electronegative.
2. Conversely, the alkyne anion does have a significant electronic stabilizing quality. Since an sp hybridized carbon (50% s character) is involved, the electron pair is held closer to the nucleus and has greater electrostatic stabilization. Thus, electrostatic stabilization of an electron pair (as part of a carbanion) can be seen as directly proportional to the s character of the carbon hybrid orbital (all else being equal): sp3 (25%) < sp2 (33%) < sp (50%).