How long does it usually take to receive a one-year work visa after application in Thailand?

Hi,

I am currently working in phuket on a non immigrant b visa, the documents were submitted on april 10th for the one year visa and immigration stamped my passport till 24th may in order to get the one year work visa.my questios are

1)Do you usually get the one year visa by the date that is stamped in your passport?

2) If you do not get the visa by that date.... does immigration give you an extension on your by visa until they have finalized the one year visa?

3) how long is the extension on the b type visa given for if there is delay?

4) does any one know how long the delay is in them issuing the visa if the date that is stamped in the passport is expiring?