Maybe I'm too late in here, but I have created a complex Access Control with all these features and more with Arduino Mega 2560 compatible with Wiegand 125khz, Mifare, HID and more...
I get started with Arduino UNO, with one reader, and now mi project supports 4 on-board readers plus "unlimited" wireless readers (so far have tested with 10 with the range of 300 meters with walls or 1km without walls)...
The system can work on both mode Online or Standalone, and in standalone can store up to 3000 users access (I have tested with 10.000, but after you get more than 4.000 / 5.000 the system get's slow on standalone mode, so I decided to lock up to 3.000 to keep the system working fine!)
I have the system working for about 3 years without interruption / problems with about 100.000 users readings every day!
Also, the "event log" you can log up to 20.000 logs events (I have done up to 100.000 but the system get slow and may craches...)
I have spend about 2 years researching, and start from scratch to get the first prototype working!
So, it's possible to do with Mega 2560!