I used to base my PA28 there last winter in hangar #12 and can confirm that they treat the security and access to the restricted zone über-seriously. They have one LOT Polish Airlines rotation a day and aspire to be a "commercial airport". Previous director was demoted for allowing unauthorised access to the restricted zone. So although no absolute guarantee of security, you can at least be certain that your aircraft will be much more protected than anywhere else around. By the way, ask them about hangar #12, it should be easily available for a single use for 5 days.
My PA28 is now at Przylep EPZP and I park it outside rather than in a packed hangar as I want to avoid getting the hangar rash. There doesn't seem to be ample space in hangars, perhaps your aircraft could be squeezed into a corner, but that way you will be facing a choice between a break-in to the cabin (outside) and a dented wing or aileron (inside). No physical access restriction at Przylep in any way, shape or form. You can walk onto the grass apron or runway without even crossing a fence.
No Avgas available at Przylep EPZP due fuel trade licensing issues, they can only fuel their own aircraft, and Babimost EPZG has the most expensive Avgas this side of the Elbe river I think.
Any questions, PM me.
/h88