Ph, th, ch are aspirated consonants in ancient Greek and Latin, pʰ tʰ kʰ phonetically (IPA). Obviously, there must have been variation. (I personally like "th" as in English "the"). In English in these words, principal, tentative, carcase, they're the sound of the initial consonant but not when the consonant repeats later in the word but I think that's to do with stress as well in English.
As for ch k and th t and v always w (until later), yes, but not "eu" as we pronounce "eu" which is like "ee[as in pee but short]-you[with the y as it's own discernible sound]" in English, but more like "e[as in bet]-oo[as in coo but short]" in Latin and as a diphthong, I would say. "Europa" is "youropa" in English but not so in Latin (eurōpa in Latin but not ūrōpa either in Latin). I would say, "eu" starts with a short "e" with your lips in the position for a short "e" (tight and wide) and then become a short "u", in shifting the lips forward and rounded to complete the sound. It's simply an "e" plus a "u" merging together as in any other diphthong. With the other diphthongs, they are pretty much the litteral sounds of the letters, too, in a nice blend, in my thinking,—provided you believe that long and short letters in Latin have the same sound, where the sounds of short letters are truncated long sounds.Aevo antiquo, latinè ut graecè (at variè) ph th ck habent haec sonos aspiratos pʰ tʰ kʰ phoneticé, ut sonus anglicè primae litterae consonantis at non in medio repetitae in his (quoad anglicè et ad vim attinet, nisi fallor): "principal, tentative, carcase".
Non ut "eu" anglicè, "eu" latiné.
Per e brevem vocalem incipit "eu" diphthongus, per u brevem terminat. Eodem modo conficuntur omnes diphthongi, ut opinor, qui credo eundem sonum communicare et longas et breves vocales, quo sonus brevis sit is longae sectum.
I'm writing in Latin hoping for correction, and not because I'm confident in how I express myself. Latinè scribo ut ab omnibus corrigar, non quod confidenter me exprimam.