1. You are correct; the small notes are editorial comments that should be given in a footnote.
2. You can use the "dotted-line slur" (dots 5, 456, 14) in Table 12 of the code. To be very clear, I would show it in both places: before the eighth notes in the upper part and after the half notes in the lower part. Be comforted by the fact that this marking will be as unusual to a sighted reader as to the braille reader.