Hi, meir.
1. Absolutely yes! ADCMP572/3 can handle the LVPECL and LVDS logic levels. Just be sure that the Vcci = 5.2V.
2. The Input Voltage Range (IVR) in the datasheet determines the input headroom or footroom from the supplies that is required by the comparator. This means that the computed 2.1V on my previous post is the maximum allowable input voltage. If you exceed to this value, an output offset or other unwanted effects may be produced due to saturation of the transistors. To avoid this unwanted effect, always take note of the IVR. This IVR is subtracted from the Vcc,Vee or gnd because this is dependent on the supplies used. Similarly, your output swing depends on the OVR and supplies.
Regards,
Anna