Hi folks. I have several questions about surveillance cams and stuff related to them:

1) Are there weatherproof wireless security cams? If there are, do they work via Bluetooth or WiFi? What is the range of their signal?

2) How do they produce the 4-in-1 image on the monitors wherein you see 4 different camera images on each quadrant of the screen? Is it produced by the monitor itself or a separate video device?

3) How many hours/days of video can a regular DVR store?

Trying to set-up a home security system. Thanks.