1) After getting the GC through a sponsoring employer, is there any procedure to indicate that the future job is accepted by the employee. I mean switching from H1B to GC status is just based on letting the employer know about the status or is there any paperwork needed to be sent to USCIS?
2) Also, based on getting a green card, is there a stringent requirement of payroll checks? This is based on the fact that H1B employees have to maintain the payroll constantly (based on my knowledge). I am asking this in case I want to take a vacation for some time in case I get my GC?
3) After joining the sponsoring employer, if on GC, more opportunities come by, is it allright to consider those opportunities? What is the timeframe for USCIS to consider that the employee did have the right intent to join the sponsoring employer?
A1) There is no formal procedure other than joining, preparing a Form I-9, being on the payroll and actually working.
A2) You can behave like you would in any other permanent job - take vacations, etc.
A3) That question has been answered on my blog. See http://forums.immigration.com/blog.php?b=36