Anonymous participant ok, strange question to ask about salary negotiations. As Greg said check thru Jakarta posts and apply accordingly. You not the first to be rejected and then succeed 2nd time around
some would if it guarantees an extension. You can do same day border run for similar/cheaper price but there is a definite market for it as with the other visa extensions.
They would need a very good relationship for sure. Not seen such a service offered so there must be a reason why. Maybe the extension for DTV must be by the applicant at the moment. Maybe in future agents can extend instead of the applicant.
Investment income is income. You can find posts on the main DTV group on FB where online investors, stock, crypto etc apply for the freelance option of the DTV