Thanks, access from another location is optional right now. As long as I can record and keep for a week as anything I can use the videos as evidence. Something with good night vision and picture quality is a must... I was looking for a system with 4 cameras.
How long you can keep it depends on recording quality, hard drive size and the number of cameras. The new DVRs use H.264 recording, which uses the hard drive space about 25% more efficiently.
I was doing a camera/DVR job last year and it was the first one on my own where I spec'd everything and did the whole job. I had installed cameras before but didn't know as much about what makes a good camera or DVR and how to set them up effectively. It was a very steep learning curve but it's not rocket surgery.
Use 24VAC cameras- DC power supply suffers from voltage drop more than AC supplies and since many of the camera power supplies output 24VAC, you would need an AC-DC adapter, which drops the voltage to 12VDC. On long cable runs, it causes the voltage drop and if P=IE, I must increase if P is to remain constant and E decreases. This causes the cameras to run hot and fail.
Look for cameras that have an internal heater to fight condensation if you're in a cold place.
Most new DVRs are capable of what's called 'Pentaplex' or 'Triplex'. This means they don't disrupt the recording when you view the recorded video or stream it online.
Oh, yeah- find out if the online seller is authorized by the manufacturer to sell online. Most aren't and the company usually won't honor the warranty because of this.