You might get a job offer over the phone.
Employers usually ask applicants their reasons for leaving a previous job. Potential employers may call the previous employer for a reference.
Yes, if it's true.
The amount of time that it takes a potential employer to call varies from employer to employer. Some call quickly within days, and some may take up to a week or even a bit longer.
Most employers will want to talk to your previous employer in order to get to know how you work and some of the qualities you posses. It is always a good idea for you to respect your employer as they may very well influence whether you get the next job or not.
Yes. However the previous manager does not have to comply.
No, you should go directly to him, do not call unless you are desperate.
You can call, but without permission from him, they are unlikely to discuss this sort of thing with you.
how are you doing
If you initially declined a position you can still attempt to accept it. Call the potential employer as soon as possible and state your reason for declining and that you regretted it and you would like an opportunity to work for them.
They can call your last employer and ask.
You should not mention anything negative about a previous employer in an interview. You never know who the interviewer might know, or who they might call to verify your application. Harping on the negative also makes you as the candidate look a bit sour and pessimistic.
"What if previous employer will not return a call for a reference?"