1. sans que ceux-ci donnent lieu à des critères chiffrés : I think you translated that correctly.

2. On the final question, my feeling is that refusal would be either rejecting the advertised position out of hand (refusing to go to a job interview the agency person wants to set up), or rejecting a firm offer from the employer after interview.

It seems pretty futile to me. It's attempting to force people to move down instead of helping them to move up. Employers encounter difficulties in finding certain categories of skilled personnel because there are fewer people with those skills than jobs on offer. Many jobseekers are low- or unskilled, and there are more of them than the unskilled jobs on offer. Without investment in training, coercition seems unlikely to achieve anything.