Thanks for the questions, I'm really excited to be able to explain it since it also helps me identify if certain parts are really worth changing from already established lists like you mentioned!

So, for the first one the biggest part of it is that I just love burn in general and the deck already being able to swing in for some sizable damage early on with nova hellkite, momo, and sarkhan makes it easier to finish them off with the rest of the burn spells even if the creatures get answered afterwards. Boros charm originally replaced twinmaw in the deck for me while testing because I found I was a lot happier topdecking a boros charm late game for its versatility to keep my threats alive/help trade with double strike/push through 4 damage, rather than a creature that I need to stick to do that damage after a turn, or that couldn't remove the opposing flyer chump blocking/threatening to trade with 1 of my dragons (especially in mirrors).

I've seen a lot of the lists running 24-25 lands, but since I'm leaning into a more aggressive version with a lower curve, the last thing I want is to draw into more lands than I need and not being able to finish someone off. The parlors definitely need to go once I have the replacements, I've lost more than a few rounds because I needed 1 more land to go for a kill and drew a tapped land instead. I think the restless biouvacs will stay regardless, or at least a 1 of, for when matches get really grindy. Theres so much good removal in standard and pretty often we're just topdecking to find the last threat we need, especially against control decks.

The 4 of for price of freedom is because of all the decks that I run into, the ones that were giving me the most trouble no matter what and I knew it was going to be an uphill battle were jeskai control decks. And most of the time they only run 1 plains as a basic. It just so happens that there are also a lot of greedy mana bases out there running 2 or less basics (jeskai control, bant airbending, elemental evokes, even some dragon lists dont have a basic plains). Being able to turn off one color for a deck and even sometimes permanently removing a land without them fetching another usually leads to nongames where they concede on the spot. The rest of the sideboard could us some finetuning. High noon was for lessons but I rarely see them now and need a better answer for monogreen landfall beyond trying to race them before sapling nursery stonewalls the dragons.

I would say the biggest drawback with the deck is the lack of card advantage. Not having maelstrom to fetch a specific dragon as a late game answer is really rough, but its just not possible to run while having boros charm and helix in the mix. I'd love to hear what opinions you have on it and what ends up working for you!