In general you need to look for a UL 458 inverter with a transfer switch or match one up with a external transfer switch. To tie into your existing set-up it would be better to get one that requires hardwiring, although some also let you hard wire off of the outlet they have. a lot of how you wire it up will be driven by the inverter and/or transfer switch instructions.
As far as GFCI circuits, any non hardwired circuit, should be covered by a GFCI receptacle. You can wire downstream receptacle to be covered by one GFCI receptacle.
The neutral to ground bonding should be handled by the transfer switch. In many inverters with internal transfer switches you usually have a standby mode. This allows you to be plugged into shore power, and if shore power were to fail the inverter will pick up and start to provide AC, in this case the ground to neutral bond needs to move from being back at the Shore Power Panel to the Inverter.
This is how it is done in the Magnum Energy MS2000
-greg