What is going on with the transformations?? SSGSS is not stronger then SS1?
This is a pretty elaborate question, however , I will try to break down the answer to every sub-question in points.Firstly,  transformations are multipliers. A stronger transformation, multiplies Goku's power to a higher level. The Super Saiyan God transformation, is a higher multiplier than even the Super Saiyan 3 transformation which is very obvious in the Battle of Gods arc. Hence, Super Saiyan 1 is not stronger than Super Saiyan God. However, you have to remember, Base Goku can get substantially stronger. Current Base Goku, is stronger than Super Saiyan 3  Goku from the Buu Saga(Based on Base Vegeta vs SSJ3 Gotenks fight// Goku and Vegeta are relative in strength). So technically, it is possible for Super Saiyan Goku in the future, to be stronger than Super Saiyan God Goku from the past.Beerus was excited about getting an opportunity to fight the Super Saiyan God and was merely toying around. He isn't afraid of Super Saiyan Blue. In the manga, Mastered Super Saiyan Blue Vegeta is taken out by Beerus with a single shot. Beerus is one of the strongest God of destruction across the multiverse. This was established in the fight between all the Gods of destruction in the manga.Before I get into Broly, I would like to talk about Frieza.  He was weaker than Namek Saga Goku who is weaker than Buu Saga Goten and Trunks. However, when he returned in the ROF saga, he was stronger than Super Saiyan Blue Goku and only lost because of the Stamina drain issue.  Now if one were to look at your argument, where these powerful transformations aren't to be rivaled , Freiza ideally would have been one shot by Base Goku and the entire ROF arc/ Movie would've been over in 5 minutes. It is very important to note that Broly is being introduced as a new character. The Broly from the previous 2 movies isn't canon. This character for this Broly is being written by Toriyama himself. Hence, you shouldn't classify Broly's transformation as a lower transformation until you actually see the movie.Broly is the antagonist for the new Dragon Ball movie. Based on your logic, if the main antagonist is weaker than a protagonist in a Dragon Ball Series, there would be no plot, no fights and basically no content. If you want a show where the protagonist one shots every antagonist and the story progresses, I recommend you watch "One Punch Man".The Dragon Ball Series revolves around Goku and the rest of the Z fighters. Hence, we get to see these fighters become stronger and progress in power and achieve certain milestones. We do not see the same with regard to the antagonists. We have no idea how Jiren grew so strong by his own and was able to rival/surpass a God of Destruction. We also don't know how Toppo grew substantially strong enough to be chosen as a candidate to become a God of Destruction. We just have to accept it as some characters are always going to be a lot stronger than what we think, while some are going to be weaker than what we think based on what the plot dictates.If you watch the trailer, Vegeta and Goku do not recognize Broly. Hence, he is being introduced as a new character. Vegeta also mentioned that he was growing stronger during the course of battle. Maybe he can be compared to Goku Black(who was relative to SSJ2 Goku at the start and grew stronger than SSJB Goku easily)? I personally would have a problem only if Broly were to rival or be superior to Mastered Ultra Instinct Goku, considering that is a level above the Gods. I don't see why Broly shouldn't Surpass Super Saiyan Blue considering the fact that there have been characters who have surpassed the same.