There are CONverters and INverters. INverters change DC (battery) voltage to AC (household 120 volts). CONverters take shore power (household 120 volt AC) to make DC to power your lights, radio, fans, etc AND it charges the batteries.
Going with a Progressive Dynamics converter is a wise decision. This converter uses plain old house power to make pure DC power.
First answer: When choosing a converter, there isn't a choice of sine waves as that is a choice when buying an inverter.
So, onto your Second question about amperage. If you aren't increasing your battery capacity, pick a PD converter closest to your old converter's output, but not less. More output isn't necessary for a stock set up.
2000 Cherokee 29BH with 6V batteries, LED lights & 400 watts of solar power, flipped axles and raised. 2007 Tundra 5.7L DC-LB with lots of mods. C-co, 8/158th AVN Maint.