To make several changes at once, use the "edit" button in the top left of the issuevderail screen to open the editing modal.
Yes I can compose my reply in another editor and paste it once it's final. However, IMO an issue tracker is something you use so often that working around these small issues comes at a high cost to me when it should not.
Is this the query language that you are mentioning? I don't have experience with it but from the documentation it looks very limited.