Re: invertor question
Sometimes the inverter is wired to only a few outlets and/or a few built in devices. Check the manual or wiring diagram to ensure that where you are plugging in is powered by the inverter. Also, check all the breakers and fuses.
The primary limitation is your battery bank. If you don't have a lot of battery power, having a bigger inverter is a waste of effort. The next 'limitation' is what you want to power by inverter. Add up the power 'needed' and round up. If the inverter was installed at the factory, then you probably want to stay with the same size, unless you really know what you are doing (if the wiring and fusing is based on one size, just replacing it with a bigger one could cause problems).
Finally, there is the 'type' of inverter. The cheapest ones put out a square wave, triangular wave or 'modified sine wave' which are very 'dirty' electrically ('noisy'). This can cause some devices to work 'funny' or even damage some devices. The best inverters are the 'true sine wave' which provide power as good or better than comes out of the wall. Unfortunately, these tend to be rather more expensive.
Also, the bigger inverters often have battery chargers built in. You will need to make sure the new one matches the old one in this regard, or modify the wiring to compensate so the battery charging continues to work.