No.Certainly in any immigrant's mind when choosing between the two possible destinations of north or south there must be a decision of conscience if slavery exists only in the south.
Just No.
This isn't just extremly simplistic (slavery existed for some time also in the North, did not exist every in the South and did not exist exclusivly in the South among all available areas for immigration), but it is also wrong.
Slaves are expensive.
That is like saying that everybody immigrating to the Ruhr area is secretly hankering for his own foundry (and a foundry would be more use at that).
Slaves are only cost-effective if you are exchanging cash (and quite a bit of cash; about 5000 to 10000 dollar for a slave) for a field hand in the cash crop business. If you are running the family farm that is simply not cost-efficient. A farm hand or an indentured servant would be much cheaper and could also be paid in the produce from the farm, reducing conversion costs.
Or not. Again. Time is a factor here.While a certain type of white society loved the idea of slavery to profit by, the majority abhorred the idea, its practice, and the seemingly despicable persons who engaged in it.
I find that doubtful.It is precisely for this reason that a Mason Dixie Line occurred... because certainly slavery would also have been profitable in the north to work mines, factories, etc had the idea even been tolerated there.
Mines, maybe, though additional provisions would have had to be made to ensure survival of the slaves in the winter (in the relativly mild southern winter as much as half the slave population died of exposure during the winter. I can only imagine how high the quota would be in the north in the moutains) which might very well eat up all profit made from not having to pay wages, while using white 'free' miners and a company store scheme also gets you quite cheap labour (which is another flaw of your theory: Those upstanding people north of the Mason-Dixon-Line had absolutely no qualms about profiting from 'free' peoples misery). For factories you would want, up to the invention of the assmebly line, slightly more self-motivated and skilled labour than the typical slave could provide, which you would alos like to hire and fire as appropriate... also something not really possible with slaves. IIRC the Tredegar Iron Works, THE southern iron works run with slaves had trouble with huge labour costs even though they primarily used slave labour.
You don't remove the Malaria. The Mason-Dixon-Line is more or less the upper northern limit for the malaria mosquitoes in the US.So, if you remove the stigma of slavery from the south, you remove a definite objection many people had to living or working there. So more white settlers would be the result.