This strongly depends on the individual concerned. It only affects perception. This may cause any mood possible, since psilocybin constantly attaches to many of the serotonin receptors inside the brain.
Yes. Both marijuana and magic mushrooms are hallucinogens (marijuana is a very mild hallucinogen, though), so smoking marijuana while on magic mushrooms will enhance your high.
No, some mushrooms are so toxic that handling them, getting the toxin on your hands and then eating something without washing your hands can cause grave sickness or even death but the toxin does have...