The AP1117 series of regulators might be a match (they are commonly available and low-dropout I believe - possibly
even 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 it
is in the circuit (if Vin, then 25V or more would be wise). But I might be wrong - the MOSFET circuit may require
specific voltage response (its used for power source detection and switching I believe). If you are not needing
supply switch-over then its probably not needed.
The auto-voltage mosfet switch is only being used in +5vdc service, it doesn't see the Vin voltage level at all.