Tks; more simply my first question was:
1) The changes that Princeton says exist in verbal system is present elsewhere or on the rest of cases the quality of a consonant is kept everywhere "until the end"?
2) My second question is born from a misinterpretation of a somewhat ambiguous phrase in
www.alphadictionary.com/rusgrammar/verb.html finally made clear. Abt "The rules of Stem-Ending combination", where says: If the stem ends in a consonant and the ending begins with a vowel or v.v., there is no problem, both are kept. When two vowels are together, one of them, usually this of stem disappears. "Consonants are different, however; they are stronger than vowels and all but four of them put a fight. The weakings are й, в, н, м; like vowels they simply vanish from the stem in the presence of a vowel [like a vowel before another vowel, say I] on any ending." Well, but these consonants й, в, н, м disappear just before a consonant (дела[й]ть, жи[в]ть) not before a vowel (this was my mistake), so it is clear.
Thanks