checkout this video to get started on adding Relume to an existing project.
https://relume.notion.site/Using-the-Relume-Library-on-existing-projects-c29fbf019b6d400892cd671581c8fab8?pvs=4
As for your second point, there really isn't any way to go from Figma to Webflow in any kind of automated way besides pasting in the components from the site builder or library and then applying the same styles or design/layout from Figma.
It'll take time to learn Webflow and being able to manipulate the elements to match designs but you'll get there! And along the way, if you have any issues at all, please reach out!
