Just finished the first book and I feel like I’m missing something

Hi folks! I just read the first book and it feels like there are still a lot of loose ends that aren’t tied up. I’m not 100% sure about continuing the series, there were parts that I found interesting but I had a hard time following some parts of the plot. I don’t mind some spoilers but if the answer to these is “keep reading” then please let me know. I am not sure if I just missed something or if these things never got resolved.

By the end of the first book-

1) Do we know how the Three Body game was made? There is so much information in it I don’t see how it could have been programmed without a lot of back and forth with the Trisolarians and that would have taken a very long time. Not sure if I just missed this or if it wasn’t explained yet

2) What happened with the countdown and the pulsing of the CMB?

3) If the Trisolarians know so much about Earth and the development of our technology then why were they waiting for a signal? It seems like the princeps already knew what they needed to know to decide to invade before the first message was received at Post 1379.

Thanks in advance for any help!