Couple of questions - financial/work - spouse settlement

So hubby arrived in February and is doing better than expected! I'm struggling more with being back here than he is with being here!

Now trying to help my son and daughter-in=law with their spouse settlement paperwork.
QUestions mostly around job/financial requirement.

Last year he earned 39000USD (Jan-Dec)
He left his US job December 16, 2016 to prepare for coming here. He started new job here March 20, 2017
He is worried how UKVI counts the time he hasn't worked - do they count from the day he left his old job as time not working or from the end of December as he earned money during December? It may make a big difference to the outcome!

Also, although he has started a job here he is not sure if its a good long term fit.  Is he allowed to take a fixed term (1-2 year) contract job or can it only be permanent jobs he can do?

Thanks in advance.

They will count back 12 months from the DATE OF APPLICATION to determine if he met the financial requirement in the US.  So if they apply April 1, he needs to have made a minimum of £18,600 between April 2, 2016 and April 1, 2017 (in his case December 17, 2016).  Sounds like he will easily meet that requirement.

It's fine for his UK job to be a fixed contract, just so long as it is continuing for the foreseeable future (which is certainly the case for a 1-2 year contract).  Just be sure he does NOT leave that job until his spouse has landed in the UK.  Easier to "not go there."  As soon as she's landed, he can feel free to quit and find something that's a better fit.