I have a bit of a technical question for those who are liturgically-minded:
At the Paraklesis to the Theotokos, usually sung during Lent and around her other feasts, there are a series of megalynaria sung at the end of the canon ("Higher than the heavens", etc.).
My question is: if it is a Paraklesis to a saint (not to the Theotokos), are the megalynaria for the Theotokos still sung? Or do we sing
only the megalynarion to the saint?
I hope this makes sense. Thanks!

You sing the megalynarion of the saint and of the church in which the paraklesis is being sung. At least that's what I've seen.
What other Paraklesis exist besides those for the Theotokos and Advent?
There are many parakleseis (plural). A very popular one is to St. Nektarios. These are modeled on the Small Paraklesis to the Theotokos.