not entirely sure what you're asking about, past life regression is possible, though i don't believe people who say they were Cleopatra or King Henry in a past life, since things can be planted in your head to make you think so. past life regression, in my opinion, is best done on your own.
your partner thinking they were an Egyptian in a past life, i'll say is possible. there's a theory that the reason we love certain time periods [like Victorian, Egyptian, Elizabethan] or learning about certain things [Salem trials, Vlad the impaler] is because we were there in a past life. sometimes, yes, we could find something from that life we cherished and it could unlock memories if the bond was that strong.
this all being said however, your partner shouldn't put so much emphasis is their past life. it's cool to find out this stuff, and it's fine if they show interest in it, but it's the past, this life is the one you need to live and experience, you already experienced Egypt in the middle kingdom [or whatever time they apparently lived] there's a reason you live this life, so don't spend it looking back.
not sure what a quija is, do you mean Ouija Board? there could be a spirit messing with him, but i don't know what the gain would be. just make sure he uses it properly, and if you feel he uses it too much, talk with him, try and get him to use it a little less. you don't need a Ouija Board for past life work, you could do it through meditation. not all spirits are evil, the spirit could just be trying to help, or it could be bored and wants attention, just keep your eyes open is all.