Experiences & mods running the D&D Stranger Things Hunt for the Thessalhydra Adventure?

Hi folks! TL;DR - I'm running the Stranger Things starter set adventure Hunt for the Thessalhydra for Int'l Tabletop Day at my local comics & game shop, and I'm wondering what tips, tricks, and mods people employed.

Slightly longer version -

Here are some slightly more specific things I'm looking to expand, change, or seek advice on:

1. I don't like how the "mysterious warrior-princess" is used in the adventure, so I'm likely going to make her into a Companion character using the Companion System rules on DMsGuild. She'll join the party and have some minor abilities to help the party hit and/or heal.
2. Due to #1 and the possibility of more than 5 players, I'll likely bump the Thessalhydra's HP and give it a 3rd Legendary Action (but only if necessary).
3. The beginning roleplay sequences are underdeveloped, disjointed, and technically don't have an impact on the players' choices or their path through the adventure. I'm thinking of combining a few of them and creating a scene with a couple NPCs, an owlbear (to really sell the idea that there are lots of owlbears wreaking havoc on nearby farms), and a very, very short wilderness journey (from the castle where they get the quest to the village where they investigate and discover the location of the troglodyte cave). Any thoughts on a good interaction/exploration/investigation sequence all rolled into one?
4. How have people found the trog encounters? There are a LOT of them throughout the adventure (two groups in two different caves). While I like that there are several chances to interact and intimidate or subdue them without combat, there's still just...a lot of trogs! I feel like a little more variety would be nice, or just less encounter areas overall, reducing the numbers of trogs...?

(Cross-posted on https://www.reddit.com/r/DMAcademy/)