For the Agent the higher your salary u get, the higher his commission. Generally thats the arrangement, but depends, mayb they got arrangement based on no. of individuals instead of salary amount. If thats the case, the lower ur salary the easier for him to strike the deal.

But normally commission based on salary is the common one.

ANyway, thats the commission part.  If the agent is for real, they will be more concern on the candidates suitability.  If u turn out to be a bad candidate/employee after getting u in, the agent's image will be bad..

It depends heavily on how is your contract.
If you are outsourding to the company under the agent account, its not necessarily the higher salary they pay to agent will go to you, the agent might press your salary even the company pay to them quite high.

If you are under direct contract of the company and agent just help to do the recommendation and documentation, they will try negotiate for you as the higher they negotiate for you the higher commission they can get.

This is correct. Unless the agent tells you that you will be hired under the client directly, you are usually under the agent's company,  the salary are usually lower.

from my reading though out this topic.. all of u r chinese working in s'pore.. any tips for for other races.. malays/indian/etc to get a job there