Pronounciation of h

Apologies for my ignorance, but how is that pronounced? I know how to pronounce h and ht, but what about hy and hw? Does it cause any difference if one will omit the h and just write y and w?

By the way: would eht and ehyt be pronounced differently? I know, one can not write that, but just in theory it should be equal, shouldn't it? Secondly: Is there any difference between hy and harma?

Hyarma is only used at the beginning of a word, harma in the middle of a word, and halla only before r or l (hr, hl). Hyt is not a permissible consonant cluster. hy is pronounced as a breathy y (or in Gondor SH) and hw a breathy w, like in "wheat".