A priest would address a bishop in the same way that a lay person addresses a bishop - very formally as “Your Excellency” or “My Lord”, less formally as “Bishop”, informally as “John” (or whatever). The degree of formality used will depend on the circumstances, in particular on how well they know one another.
And the same works in reverse for a bishop addressing a priest - the bishop will use the same form of address as a lay person would. Formally “Father”, less formally “John”.
No, it isn’t. But the OP doesn’t specify any particular country. “My lord” is used in some places and “your excellency” in others, and no doubt there are places where both are current.
I’ve heard, in German, the standard form that we use for any other grownup man, namely Mister plus surname, also used towards a priest or a bishop. Alternatively, you can replace the surname with the title, so “Herr Bischof” would be OK. The “Your excellency” thing exists, but would be used only in really formal contexts, like when you give a speech and you explicitly welcome a bishop as a guest of honour.
In my experience, non-Catholics usually address priests as “Father”, or “Father <name>”. And when I address Protestant clergy, I usually use “Reverend”.
There has been a shift lately, in that it used to be that most priests went by “Father Lastname”, but nowadays “Father Firstname” is more common. An exception is that many monastic orders have always been “Father Firstname”, though in that case the first name used often isn’t the name he was given at birth, but one taken on joining the order.
Only some bishops of the CofE, none of the RCs, and “Your Grace” as a formal address (I think) applies only to Dukes and bishops, not members of the House of Lords per se.
It may not be the most reliable source, but Father Ted (set in the Republic) uses both “Your Grace” and “bishop” to Bishop Brennan* (who takes umbrage at being called “Len”, where it’s not uncommon in the CofE to talk about “Bishop Alan” or “Bishop Sarah”).
Really? As a non Catholic I definitely wouldn’t feel comfortable calling a priest “Father”. Reverend seems different to me because it’s just a title but “Father” has certain implications that I wouldn’t be at all comfortable with.
I’d also balk at titles like “Your Holiness”, “Your Excellency”, or “Your Highness” (for a secular ruler). They all imply a level of buy-in that I’m not at all comfortable with. I guess I’m lucky I don’t have to rub shoulders either priests or kings…
I have certainly been told to do that, but I find it really, really uncomfortable to address anyone but my dad as “father”, because they aren’t my father no matter what their religion tells them. I did it a few times when I was younger (not yet legally adult) and less sure of myself but not anymore.
Indeed. Dukes are “Your Grace”. Other peers (marquesses, earls, viscounts and barons) are all “My Lord/Lady” or “Your Lordship/Ladyship” (irrespective of whether they sit in the House of Lords).