A definition of Blue Tooth Low Energy 4.0 is proposed on
https://en.wikipedia.org/wiki/Bluetooth_low_energy

This protocol of communication with electromagnetic wave in the frequency range 2,4-2,5 GHz, allow to exchange between data and connected devices a microphip (and antenna). All of this responding at Bluetooth Core Specification Version 4.0. In reality the majority of smartphone, touchpad, connected objects and operating systems like iOS, Android, Windows phone and Blackberry are compatible BLE 4.0.

The iBeacon emit a unique identifier under the shape D’UN TRIPLET, defined by Apple for to be compatible with devices of the brand : proximity UUID, Major, Minor.

She is detected by an installed application on Smartphone. In which the unique identifier of the beacon iBeacon was declared at the time of the development or on the back office of management.

The user must be accept the location on the application and let the Bluetooth on standy.

The iBeacons require device mobile (Smartphone, touchpad) having a Bluetooth 4.0 microchip (other name BLE). A list is proposed here :
http://en.wikipedia.org/wiki/Bluetooth_low_energy#Hardware

Accorting to you project, you will need more or less RSSI value per second. For example, if you use the iBeacon for application zone entry detection (shop, museum, bus shelters, station, lounge attent) a signal per second or every two seconds will suficient. The battery will be far enough for during one to several years. If you need to locate a moving person in the space, you will need treat many signals to have reliable values (for example emit very 32 meters) : you go a lot to request the pile. It’s better to opte for a iBeacon USB-powered, or a iBeacon high capacity pile (iBeacon in pile C – LR14).

Yes and no.
If you put a device at 2 meters of a beacon, the successive values RSSI are very different (with a gap of >30db). So it’s no reliable. However if you make the average on 20 successive points and you start again, you will have an arevage value stable. So yes, it is possible to operate the RSSI.

You can edit the settings of your beacons : change password Proximity UUID, Major, Minor, the power and the interval of the transmission signal. This settings allow you to activate the notifications or other services in an application designed to respond with iBeacons.
If you need a specific program, to spread for example a value, you can contact us for a study or encryption of your project.

Our Beacons can be set to manage their particular interval of emit : as it emits a signal evry 32 meters or every seconds for example, the energy consumption of the beacon differ. It is a live impact on life of the battery. We offer you here a method for estimating the life of the battery depending on th selected parameterization.

Yes. That requires that the beacon is a iBeacon, that is to say it emits its ID under the form : proximity UUID, Major, Minor, and value of RSSI at 1m (-50db). We deliver the iBeacons by default.

Advantage of BLE :
the transmission area is configurable from a few centimeters to 50 meters ( we established connection zone until 300 meters with a antenna directional to the outer microship).
BLE works on devices Apple (contrary to NFC).
Inconvenience of BLE :
The beacons requires a supply (NFC can supply with passive microship).

Yes. It must authenticate for access methods settings of beacon. So a third user can not chand id, the frequency and the power transmission.