new to js and jquery question about moveable/sortable objects

new to js and jquery question about moveable/sortable objects

Hi,
I am new to jquery and need some help / pointing in the right direction:
I have a list, that is generated via php and mysql
now I want the objects in the list to be moveable so I can rearrange the order of the list - so far so good, found a script that allows me to do that, but I want the elements to be counted according to the new arrangement so when I return the info into the database the new order is saved- how can I do that?
Also the single items in that list have an information on duration (in days) so I would love to have a calculation according to the re-order and an output of the date:
eg.
star-date 2016-12-01
item1 2 days - 2016-12-02 (number 1)
item2 5 days - 2016-12-07 (number 2)
item3 3 days - 2016-12-10 (number 3)
etc.
---
reorder
item2 5 days - 2016-12-05 (new number 1)
item4 6 days - 2016-12-11 (new number 2)
item1 2 days - 2016-12-13 (new number 3)
etc.

Thanks for pointing me in the right direction - even more thanks if there already exists a script that I could use that you could show me  ;-)

Best Kermit