MAX77757: Change charge current on the go, reverse polarity protection

Hello, I am currently designing a PCB with a MAX77757, and I have two questions I could not find in the datasheet or the forums.

1) I would like to change charge current with an external microcontroller (open drain outputs switching resistors) - when exactly can I change current? Can I change while the chip is charging? If not, can I change while the chip is powered via USB and battery is connected, and the chip is disabled by pulling THM to GND? If that does not work either, do I have to disconnect battery or USB before changing charging current? I can not find any information when the chip is checking for the resistance connected to IFAST, if it is something it polls digitally or if it is an analog input that affects charging current in realtime.

2) Does the chip have any kind of reverse polarity protection for the output? My device will have a cylindrical cell in a battery holder, so users plugging it in with reversed polarity is a possible scenario. If the chip does not have any internal protections against that, is there a recommended external circuitry I should use? For now I used a n-ch FET in the -BATT line, and a pnp transistor to switch it on/off depending on battery polarity. Works fine in simulation but is untested.

Thank you in advance for your help - any input would be much appreciated!

Kind regards