LT3083 as a Voc Clamp to power LTC4015

Hello,

I am using the LTC4015 with Solar Panels that have Open Circuit Voltage (Voc) as high as 42V, but the maximum voltage that can go into the LTC4015 is about 36V. So I am looking for a Voltage clamp / Regulator that can output 36V/3A from a 42V/3A power input. 

 For this requirement my search lead me to LT3083, and specifically to the high voltage regulator mentioned on the datasheet (Page20).  

Following are my questions

1. Is this a good solution for the requirement I have? or are there better alternatives?

2. For the above schematic to output 36V/3A apart from Rset, any other parts on the schematic will need changing?

3. I dont completely understand the input section FET circuitry, can someone explain this part?

Thanks.