Their relationship could start with mutual respect. Eggsy respects Princess Tilde's position and she respects his skills. As they spend more time together on missions or at diplomatic events, they start to have a deeper understanding of each other.
One plot idea could be that Princess Tilde gets involved in a dangerous mission with Eggsy. Maybe she discovers some crucial information about a new threat to the world and teams up with Eggsy to stop it. They could face many challenges together, like fighting off highly trained assassins in a foreign land.
Definitely. Kingsman originated from a comic. The comic provided the framework and characters that were adapted for the big screen, while also allowing for some creative expansions and changes to suit the cinematic format.
Kingsman 3 is purely fictional. The story and events are crafted by the writers' imagination. There's no real-life basis for it. The action, adventure, and spy elements are all made up for entertainment.
I'm not sure exactly, but you might be able to find that information on the official Kingsman comic publisher's website or some dedicated comic databases.