Can you explain the difference between focus and priority, and lets say im a showdown if i play an action technically i still have to pass focus after that right

They're different layers: Focus is "who may start a chain in a Showdown Open State," Priority is "who may act right now" (including playing Reactions on an existing chain).

Focus is a "home base" tracking tool — it's what lets you play an Action when the chain is empty. Priority is the singular exclusive right to take any discretionary action at this instant, and it bounces around as players react, pass, and resolve (Rule 312–313). They come as a bundle — gaining Focus also grants Priority (313.2) — but you can pass Priority and still keep Focus (313.3).

Yes, in effect — but you don't "pass" it manually. When you play an Action in a Showdown, you keep Focus for the entire chain. You pass Priority (often to your opponent, then back) to let the chain resolve. The moment the last item resolves and the state returns to Open, Focus automatically passes to the next player in turn order (Rule 346, 347.1.b). So you can't start a second chain back-to-back — the opponent gets first crack. The only "manual" pass of Focus is the Pass action with an empty chain, which is what eventually closes the Showdown (347.2).