@Bae_Suga1123 As for the blueprint, the blueprint was extremely important, but its significance is now entirely symbolic, thanks to Sana's actions. The blueprint was the physical manifestation of Jungwon's plan to help Sana destroy Jay's control. It contained the details for sabotaging the Annex security system during an event to create a window of escape (the original "Red X" plan). It was important because it was the only leverage the allies had against Jay, and it was the evidence of Sana's alliance with Jungwon. But sana burned the blueprint and by destroying it, she took away the ability for either side to control her. She eliminated the strategic conflict, forcing Jay to deal with the only thing left: their raw emotional connection. Its importance now is the memory of the sacrifice she made to achieve peace.
And yes Jungwon absolutely has feelings for Sana. His feelings are based on admiration for her integrity and a deep need to protect her from Jay's cruelty. He struggled with his attraction while trying to maintain his loyalty to Jay, but the kiss was an honest declaration that he sees her as a rival for his heart, not just a strategic asset. And yes Jake also confessed his love for Sana. His love is unique because he doesn't want to fight for her; he just wants her to be safe and happy. He made it clear he would not interfere with her choice, but he wants her to know she has a choice rooted in unconditional kindness.