1) Western occultists have had some exposure to Hindu ideas of reincarnation over the last century and a half, but there were detailed descriptions of reincarnation in the West before then, and they also said much the same things. I know this is unfashionable these days, but the suggestion I'd make is that these similarities happen because reincarnation is a reality, and when people do enough spiritual practice to get past whatever dogma they've been raised with, that's what they find.

2) Mediums are an incredibly mixed bag. Some are honest, some are as fake as a millionaire's worries about climate change, and it can be very hard to tell the difference. Your Ogham divination seems sensible to me: you can certainly use channeled material as a source of interesting ideas, but don't assume that it's accurate or rely on it in any way.