You are correct it is 100 rooms, not 200. I think they told us there were around 200 people there, so I think I mixed that up with the number of rooms. Most of the people there for our stay were adults, not kids, although there were probably 20 or so kids. Everyone in my party really enjoyed it. It's not something we will likely do again anytime soon because of the cost, but as a one time thing it was definitely an awesome experience.
Check-in was at 1:00pm, not 4:00pm for us, but your 45 hours is correct. They had activities starting at 2:00pm I believe. If you are up for a late night, you can do stuff from about 4:00pm-midnight on the first day. The second day you can do 7:00am-midnight if you have the energy, but there isn't much on day 3, just breakfast.
Out of the 45 hours, there is about 30 hours of entertainment and meals and 15 hours dedicated to sleep and downtime. The food there is amazing.
How long you spend at Galaxy's edge on the second day is entirely up to you. The Galaxy's edge experience is different as part of Galactic Starcruiser then it is if you just buy a park pass. You have quests you can do, there are some Disney staff interactions that only apply if you are on Starcruiser quests (e.g., you ask for something from an Oga Cantina hostess), and you can interact with parts of park that isn't available normally. For example, there are quests to interact with the droids outside of droid depot which to a normal guest are just decoration, but they activate for someone on the Galactic Starcruiser quest. One of the quests has you de-activate a machine that is normally running and your quest turns it off (for about a minute and then it reactivates). There are activities and quests available on the Halcyon for the second day; some of the quests send you to one or the other, but the app monitors your location between the Halcyon (hotel ) and Batuu (Galaxy's Edge) and adjusts your quests based on where you are.
You get a coupon for a free quick serve meal at Galaxy's edge if you want to eat there on your Batuu's day as part of your Galactic Starcruiser, but a lot of people head back to the Halcyon for food, because the food is better or on par with the best park restaurants and the Halcyon food is an experience.
As someone who has done both, Galaxy's Edge is not the same thing as Galactic Starcruiser and you won't get the Galactic Starcruiser experience just doing Galaxy's Edge. That said, Galactic Starcruiser is expensive, and I would recommend it more for people who enjoy RPG style quests, except doing them in person (It's probably considered larping, but way better than any larping I've tried). It's probably more fun for someone who enjoys interacting with staff in character, than someone who is shy. That said, what you do during Galactic Starcruiser is up to you; there are other activities to choose from if you don't want to larp. My son spent a lot of time just playing Sabaac at the table in the cantina, doing the Sabaac tournaments, and some of the kid activities like droid racing. There are some really cool part of Galactic Starcruiser like the lightsaber training, bridge training, and the "Taste around the Galaxy" dinner entertainment. Interacting with Star Wars characters as if you are in one of the movies was a lot of fun.