The AP1117 series of regulators might be a match (they are commonly available and low-dropout I believe - possiblyeven the same pinout?)Any p-channel logic-level MOSFET with an Rds(on) of 0.5ohm or less will probably do for NDT2955 - the voltage rating depends on where itis in the circuit (if Vin, then 25V or more would be wise). But I might be wrong - the MOSFET circuit may requirespecific voltage response (its used for power source detection and switching I believe). If you are not needingsupply switch-over then its probably not needed.
Why not use the same partshttp://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=NDT2955T&x=15&y=15