CoS requested under Non shortage occupation due to unavailability of DigiTech licence, now employer got the licence

Hi,

My future employer allocated the CoS to me but having three points in it to be understood well before applying:
1. CoS was applied in june for shortage occupation but had to select "no" for shortage occupation as DigiTech licence was not available at that moment.
Now my future employer is having DigiTech licence, so shall i apply for VISQA under category of shortage occupation or non-shortage occupation ?

2. Gross salary is mentioned in CoS is different in CoS and offer letter.
for example in offer letter it is 55800 pounds whereas in CoS it is 60000 pounds, please advise how to proceed in this case?

3. my start date is 1st Nov 2019 and i would like to get it changed to 18th Nov. How is it possible to do it?

Kindly let me know the answer of above points.

Thanks
Alok