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.
definitely if you are a woman
There's no real evidence that "sperm wastage" is harmful to health in any significant way.
Yes, it can kill.
The best way to prevent ingesting harmful toxins is to wear a face mask of some sort when working around the toxins. If you have a fear of ingesting toxins from common food sources you can always read the ingredient label that comes with most food.
If you are asking "Does ingesting sperm or semen make your muscles grow" the answer is no. While there may be some testosterone in the semen, your body won't process it into testosterone in you. Testosterone is produced by complex chemical processes in the body and ingesting semen does not assist this process. If you want to make your muscles grow, exercise them, eat healthy foods. Chemically, you would need to take Anabolic Steroids or HGH to stimulate growth beyond what you can achieve by exercise and diet. However these techniques have serious health repercussions. If you enjoy ingesting semen however, it isn't harmful. Semen consists mostly of secretions from the prostate and other glands, with a small fraction of actual motile sperm. Also, semen is not "high" in protein. It is mostly water, sugars, saline and other liquids that provide a good environment for sperm to live outside of the body for a short period of time.
It's not harmful at all.
Pregnancy cannot occur due to ingesting sperm.
Yes it has been proven that masturbation can prevent a certain type of cancer, if sperm keeps building up some chemicals in the sperm may be harmful if kept in for too long.
Rubbing alcohol should not be ingested in children AND adults, no matter if you are in perfect health, ingesting more than an ounce will make you feel the need to call 911
No it's not harmful in healthy males.
No
Yes , if you like its taste. It is harmless as long as the person you get it from doesn't have an STD. Your own semen is not harmful to your body since it is yours, just like tears, spit, etc. But if you are ingesting somebody else's, it depends on whether the other person has an STD. It is also a known fact that sperm is a mere 5 calories.