so this converter you talk about has enough places to run 12v set up like lights interior, the fantastic fan, usb outlets etc. then it has the capabilities to provide a place to connect 110-120 circuits such as reg outlets. then just a cord to run to shore power and the converter does the rest? is this what that does and charges battery all at the same time?
Basically, yes.
Technically there are several connections.
The shore power/AC coming to a main breaker (typically 30A) and out via one or more smaller AC breakers, generally 15A or 20A. This is what you house's electrical panel looks like. Generally one AC wire is connected to a single breaker. Typically you are using romex 12-3 wire. Each AC wire can be connected to one or more outlets or devices. If you go to HD/Lowes and get a general house wiring pamphlet, this is what you are doing. If you have a Air Conditioner(the other AC), typically that is attached to its own 20A breaker. The cord from the PD connects to the shore power. It can be 15A or 20A or 30A. Each have a slightly different plug and wiring scheme. Read elsewhere on how to handle this.
In addition the AC is connected internally to a converter. Nothing for you to do.
Your battery is also connected to the PD module. Technically a different set of circuits. There is a plus and minus 12V input. The battery is now connect to the battery side of the converter and to 12 fused DC connector. The DC outlet/connector are identical to what you would see inside your auto's fuse box. Each fused DC outlets can be connected to one or more DC loads. There is also a ground block for the DC.
When the shore power is off, the DC is drawn from the battery and no AC is present. When shore power is on, DC power is taken from the battery and converter pair AND the AC circuits are powered. If there is no DC load (nothing is drawing power), the converter is charging the batter. If there is a DC load, power goes to the load and anything left over charges the battery. Obviously, with enough devices running, the battery is not being charged. The converter is a smart converter and will stop charging the battery when the charging is done.