What is an 'ex vivo' experiment?
Ex vivo simply means "outside the normal, living organism", whereas in vitro means "within glass", usually in a cultured system.  They are not exactly same as there is no need for the work to be done in a culture system, although both are not in vivo.  Harvested tissue could be examined ex vivo without being in a test tube, or surgical systems could be tested ex vivo on artificial organ models.  In vivo requires the natural, living organism, although it depends on just how much you are perturbing the natural.

To answer your scenarios,


in vivo
ex vivo, as it is not within the normal organism, although I could understand someone taking issue with that; definitely not in vivo, which is usually for normal conditions only, even including temperature.
ex vivo
If you mean the artificially oxygenated environment of a tissue culture system, then in vitro; if you mean the artificially oxygenated environment of a lab bench with an open $O_2$ valve, then ex vivo would suffice.