Hi Thumper.
Although losing bark from the trunk isn't great, it's not the end of the world either. These are called 'mechanical injuries', and unless it's been skinned entirely around the trunk, ya still have a fighting chance.
First, take a sharp knife and clean things up around the wound. If there is a chuck of bark that is still attached, I'll try to put it back into place and use simple electrical tape. It will not re-attach, but it will keep the sun off of the wound which can be detrimental. After about 2 seasons, if the tape hasn't naturally come off on its own, just remove it and cut away any remaining bark tissue that has by now dried out. At this point, you will notice the edges of the original injury are starting to 'swell' to begin covering the area.
They've found that the 'pruning paints' and tars are inhibitors to healing as they are petroleum based in nature, thus detrimental when ingested into the tree's system. However, check with your local garden center, as there are a variety of commercial trunk wraps availiable that are organic.
Finally, don't worry too much about any sap coming out of the wound. In some species (evergreens ) it's actually a defense mechanism.
As for your cherry, you're doing the right thing to raise the canopy. Just I guess, but it sounds like a Schubert (leaves end up red?). Suckering is in their nature, so try and keep the trunk clean. Also, the Prunis family (cherries) are notorious for suckering, paticularly from the base of the trunk. It's a pain in the azz (I have one in my own front yard and it's a weekly process).
What you may want to try is to take about a 12" length of something (weeping tile is good) to cover the base of the trunk. That way you can get in there with a trimmer safely.
Ok, I'm done..........sorry for the novel!
Tree