Thank you for sharing your questions.
I compliment you on finding in NBA's archive of webinars an answer to your continuation indicator question. I trust you found a reference to the third paragraph under #4 in BANA's Provisional Guidance on Transcribing Mathematics in UEB, which says,
If you make reasonable divisions following the above guidance, the dot 5 continuation indicator mentioned in GTM 1.4 will not often be needed; the meaning or format should make it clear enough that the expression on the new line is a continuation of that on the previous line, e.g. it will typically start with a comparison or operation sign.
As for your superscript question, the y that follows a superscript 2 is not in the superscript position because the "2" is the "item" that the superscript indicator affects. In other words, according to #8 in GTM 7.1, the effect of the superscript indicator expires after the number.
Please let us know if you need anything more or different.