1. How big is the SD card it support?

It supports up to 32GB.

2. How long video can it record with 2GB SD card?

It can record 1 hour video with the highest resolution of 1600x1200.

3. Does it support alarm input and output?

Yes, it supports.

4. What is the default IP address, user name and password?

IP address: 192.0.0.64
User name: admin
Password: 12345