1) Meant that the medical tests would be first done in your home country as "pre-employment medical" followed by the tests in the UAE clinics on arrival. The pre-employment is only for visa issuance but the UAE medical is the real one which determines whether the visa will be stamped or not
2) Like you said, it is really case to case. And depends on the magnitude of the scar and how visible it is
3) Basically if they find a scar, they would want to do either a skin or sputum test to confirm it. This usually takes some days, say a week. During this time, you are not in the hospital - why would you be? unless you have active TB. Once this is done, then the decision is taken
4) This was announced in all UAE newspapers a year ago I think and you can google search it. I don't think they updated it on the MOH site. In this part of the world, all the ins and outs and do/don'ts are not clearly documented
5) Medical fitness for YOU is part of the offer acceptance. And the contract you sign, will have that clearly listed i.e. if you fail the medical, your offer is withdrawn or contract cancelled. For your wife, they won't ask for anything. The reason I am asking to disclose is that while it has NO impact on your job offer, at least it's a conversation starter with your employer to let them know that their support is required for getting your wife visa through in the future. What if you land, get your visa and your wife has an issue and at that stage, your employer says that it is your headache not ours?
6) Well as far as the rules stand now, she definitely won't be able to get a work visa as a "new" visa applicant with a lung scar. I am referring to whether they will still consider her as a "new" visa applicant some years down the road when she wants to transfer from a dependent visa to work visa. You never know how that can go or maybe they relax the laws even further
Yes, it is a good idea to do a check to see what it looks like.