Did you find any evidence to support that Krishna is sanskrit for Christ (or "the christ")?
Krishna is Sanskrit for "black, dark", probably referring to the dark skin color of Krishna as he is commonly depicted. It doesn't have anything to do with the Greek word for "anointed". A sort of folk etymology (http://en.wikipedia.org/wiki/Folk_etymology) has been popular since the 19th century that has tried to derive Christ from Krishna or vice versa, resulting in novel spellings like Christna which attempt to assimilate Krishna to Christ (Wikipedia: "Folk etymology is particularly important because it can result in the modification of a word or phrase by analogy with the erroneous etymology which is popularly believed to be true"). There are many similar modifications in popular writings; I have seen Arjuna, the name of Krishna's companion, spelled as Ar-john by popular writers -- ostensibly to suggest a relationship with the biblical name John even though the names are wholly unrelated and the modification is quite a blatant attempt to create a similarity where none exists (as there is no philological reason for spelling the name that way).
Did you find any evidence to support that Hesus was a Druid god?
Sure, of course Esus/Aisus was a Celtic god. But what does a god from a distant foreign land who cuts down trees, who received human sacrifice, and who was identified with Mercury and Mars have to do with Jesus? (See http://www.geocities.com/chronarchy/mjournal/patrons/aboutesus.html which presents most of what is known about this poorly-attested god). I think the only reason why an obscure deity like Esus is even mentioned is that the name bears a superficial similarity with Jesus. Of course, the two names have entirely different etymologies and there is no linguistic connection between them. It would be like identifying the Canaanite rain god Baal with the Hawaiian goddess of fire Pele on nothing more than a superficial similarity of their names. The Society for instance has long claimed that the (putative) Anglo-Saxon goddess of dawn Eostre is the same as the Babylonian goddess Ishtar. In fact, they are unrelated and the names have their own separate etymologies.
Where do these theories originate?
Probably from an eagerness to overstate things. There are indeed parallels and similarities between the traditions of Jesus and those in other mythologies, especially in terms of archtypes that can be quite widespread in different cultures. It is a tricky matter however to weigh the evidence and determine the specific relationship -- whether these are topoi (commonplaces) that may independently arise in unrelated mythologies or whether there is a historical influence of one mythology on another. Certain popular writers promoting the idea that the story of Jesus was taken lock-stock-and-barrel from other mythologies exaggerate the parallels by overstating things -- even inventing parallels where none exist. That is what gets me vocal about this; I don't care at all if there is a mythological basis of the Jesus story (indeed I believe there is, see below), I care if evidence is being distorted or simply made up. It is just the same thing with Tony Bushby's pseudohistorical fabrications about the Council of Nicaea. What I don't get is that these writers are so eager to attribute the Jesus story to foreign mythologies and yet overlook the one mythology that should be expected to have been most influential: the native mythic traditions of Judaism (whether derived from older Canaanite mythology or developed within the literature of the OT and the haggadah). Parallels with pagan mythologies pale in comparison to the direct influence that can be demonstrated in the case of OT exegesis in the gospels. The nativity story in Matthew is transparently modelled on that of Moses in Exodus and especially in haggadaic writings. The water-to-wine miracle in John is similarly dependent on the miracles of Moses in Exodus. The temptation of Jesus in the wilderness for 40 days is derived from the OT traditions of the wandering of Israel in the wilderness for 40 years. The feeding and resuscitation miracles in the synoptics are patterned after similar miracles in the Elisha cycle. Over and over again there are very specific parallels, even in verbatim wording between the OT source and the gospel narrative -- the kind of close similarities you would never find with Horus or Krishna or whatever other pagan god that might be mentioned. That is partly why I have been such a critic of the Horus = Jesus meme; people are looking for the literary origin of Jesus traditions in the wrong place.