Yes, but depending on the interactions it can get complex quickly. D3.js handles all the interactions in JS on the client. ContEx (elixir server-side charting) handles certain events (e.g. data point click) server side (see https://contex-charts.org/barcharts - turn on “show clicked bar” option). Showing data point detail, e.g. “On hover” would require client side code.
Sure, but you'll need JS for anything complex. You could use SVG+CSS to show/hide specific things like data values on mouseover but it would be a global on/off for the whole chart.
(Disc: ContEx author)