How to do a simple overcurrent protection/circuit breaker circuit for 12V 1-2A?
From your description, a device like Philips BUK9MNN-65PKK might be suitable for your purposes. 


Dual channel, so you would need just 2 of them for your 4 channels.
Inbuilt current limit and sense, junction temperature sense
Vds 65 Volts
Id 7.1 Amps
Independent channels, minimal cross-talk


The Current Sense lines will provide current / over-current info to analog inputs on your MCU.

If this specific part isn't working for your purposes, there are related parts, "similar but different", worth exploring perhaps.