Hello Lotus
Has the employer applied for their licence yet?
If not, that has to be their first course of action. It may not be approved of course, even though they have been approved under the old scheme.
The immigration rules for Tier two of the PBS have not been announced yet.
When the TWES was approved it would have clearly stated that if you did work experience for 12 months or less, you cannot return to the UK with a work permit for a year, and for more than 12 months this is two years. I would not be surprised if the new rules hold you to this agreement, but it may not be in the new rules.
There is currently no easy way round this, unless you have spent 80% of the required time out of the UK or the post is a shortage occupation and you have to be out of the UK in any case. Please see the guidance for TWES and the casework instructions.
TWES guidance
casework instructions
You are supposed to be here for work experience/training to help further your career when you return home, not filling a post for your employer. There are less stringent requirements for salaries, because you are not supposed to be doing a proper job. No ads are needed for TWES either, because it is not supposed to be a substantive/proper post. If you are filling a post, and the employer would need to replace you when you leave, then it appears that they may have been less than open to get you working for them, perhaps knowing about the lower salaries that are accepted for TWES.
There will not always need to be evidence of a recruitment campaign in the PBS.
The exact date for tier 2 of the PBS has not been announced, but it looks to be sometime in November.
I think you need to speak to your employer to find out what they are doing.
At the moment you cannot switch in the UK from TWES to business and commercial.
You are right, your profession is no longer on the shortage occupation list. It is the MAC who are deciding on shortage occupations for PBS and they have not announced any yet for the PBS, they should do soon.
Regards