[AtlUmpSteve]

At the higher levels, no. That is considered coaching.

Have you ever seen a pitching change made where a defensive coach didn't make it? If a coach makes the change, isn't s/he capable (and responsible) to tell the new pitcher what situation s/he put her in?

If there is a count on the current batter, I (as PU) will restart the at-bat by announcing the count; just as I would after any other significant delay. If asked, I will restate the outs.

As BU, my responsibility is to make sure PU knows how many warmup pitches have been thrown when you are done announcing the substitutions. After that, I get in position for the next play.