No it's not harmful in healthy males.
No, it's actually healthy. You're renewing your sperm and that makes it more fresh. Just don't go over once a day.
It's not harmful at all.
No
No it cannot, unless you are allergic to your partner's sperm. But, even then, it will not be harmful, just causing an allergic response of hives.
Yes it kills it
No it is not.
Air bubbles in sperm aren't harmful at all. The presence of air bubbles in sperm may indicate that the sperm mixed with air on the way out of the penis, or mixed with air shortly after.
definitely if you are a woman
Not unless he has a STD.
Yes it is
No, not at all harmful and perfectly natural and healthy.
It should not be physicially harmful.