Regarding lithium and MM, it says this in the ClusterBuster Files (in "Playing Well Together"):
>>Anecdotal reports suggest that lithium can greatly potentiate the effects of LSD or mushrooms, and that it can produce very unpleasant feelings. An examination of a number of reports suggested that lithium can either increase or decrease effects. The combination of lithium and tryptamines may even produce episodes that seem like, and that perhaps are, epileptic seizures. If people are taking lithium for treating cluster headaches and it is not working, they may want to talk with their doctor about not taking it any more before trying mushrooms or LSD. If people are taking lithium for bipolar affective disorder, they probably should continue taking lithium, and they should avoid taking tryptamines for cluster headaches.<<
Not everything in these older document is completely reliable, but I do believe that some others have commented over the years that this information should be kept in mind.
I'm sure that Batch will comment on your primary question, about D3.