Any amplifier you purchase will amplify every network on the band that it covers. So, for example, a 1900MHz amplifier will amplify any networks that are licensed to operate on that band, and not just your specific network. So to amplify multiple networks, you will only need one amplifier for each band, or just one single dual band amplifier.

This depends on which networks you need to amplify. If all the networks use just one frequency band, you can use an appropriate single band amplifier. However, in most cases you'll want to use a Dual Band Amplifier Kit. A single dual band kit will amplify every network (except Nextel and MiKE).

Mike and Nextel kits can only be amplified using a separate iDEN amplifier kit.