Compare scores across several measures on a radar (spider) chart - here in this tab, with nothing uploaded.
Radar charts compare people and products - skills assessments, reviews, player ratings. This one is drawn in the browser, so the scores stay with you.
At least three. Between five and eight is easiest to read.
Yes - add a column for each. More than three overlapping shapes gets hard to read; consider one chart each.
PNG at twice the screen size, for documents and slides; SVG, a vector file that stays sharp at any size and opens in Illustrator, Figma, Inkscape or PowerPoint; or copy the image and paste it straight into a doc or a chat.