I think this is the first time I've finished the Listener and Inquisitor on a Saturday. If it helps, 22 and 4 can be found in Collins dictionary, as well as the ODE.
I think I'm done but I don't understand how the first 5 words make the answer for 20. Can't see where the thematic change can be except after 'to' and that does not help me!
Yes, I read it as Penn State Univ, formed from PEN+N. Thanks, Crucifer, for the Molossian explanation: never heard of them, and it seems a bit obscure. (But I suppose it's only obscure if you've never heard of them.)
Completed quite quickly (for me) but irritated by not being able to understand the wordplay for 15d. Have the only possible answer which fits the definition.
Can also see the likely thematic modification.
Having completed OK yesterday (The theme was new to me - but might expand my re***ng). But have one blind-spot - 27A - at what point in the clue does the alteration occur? - Hint appreciated without giving a 'spoiler' to others.