Adverbs ending with "ий/ый" might be pronounced as "-и/-ы" sometimes ("/сини/", "/красны/", "/новы/"). And maybe this confuses you. In other cases "ий" is "/ий/" and "ый" is "/ый/" including "зданий", "приключений" etc.
Quite frankly, "what's the point" of specific phoneme combination is a very strange thing to ask about. I'm not sure that "ий" can be considered a diphthong, since й is not a vowel. But more importantly, you are wrong when you say that Russian speakers tend to pronounce it like /ɪ/ – it's clearly /ɪ͜j/, you can not pronounce "здани&...
The letter ф is found almost exclusively in loanwords. The only exceptions are sparse native Russian words like дрофа, филин and onomatopoeic words like фу, фыркать etc.
The sound [f], though, can be found in many native Russian words as a devoiced allophone of /в/ in words like вторник, вперёд etc.
It got there after the fall of the reduced, when consonant ...
I'll start a bit from afar.
Each segment ("sound", allophone) covers a lot of possible actual articulations. And, while it does seem like for [v] the spectrum is somewhat wider than for [f], their articulations are most similar and voiced/voiceless is the only difference which is stable across different allowed articulations. (As an aside, I would ...
Yes, [ф] is just a voiceless [в] which is practically the same as the English [v]. In [ф] there is no additional articulation found in [f] (lower lip covering upper teeth). Minimal pair:
Another voiced-voiceless pair that English speakers should be particularly careful with is [б] and [п]. Be sure not to add any aspiration to [п]: