HELP!! Whats involved in moving from Canada to the States?

It looks like my husband is going to be getting a new job in California.  Currently we live in Ontario, Canada.  

I just had this idea that perhaps folks in similar situations to what we may be heading into would be able to give me some advice on this whole terrifying process.  

Things like the differences in medical coverage, transferring cars and pets, setting up financials like bank accounts and credit cards, and how to manage those ‘in between times’, when we no longer have an income here but haven’t started with the income there!  

How about transferring government cheques, such as my disability pension here?  

THIS is the stuff that is freaking me out!