If I play a focus action to trigger Recon Specialist, this will then allow me to use Experimental Interface. Can I then use my Lando Calrissian upgrade card as my chosen free action? This would therefore allow we to have 2 focus tokens and a possible combination of 2 more focus/evade tokens (if not rolling blanks) for the price of a Stress token?

If I play a focus action to trigger Recon Specialist, this will then allow me to use Experimental Interface. Can I then use my Lando Calrissian upgrade card as my chosen free action? This would therefore allow we to have 2 focus tokens and a possible combination of 2 more focus/evade tokens (if not rolling blanks) for the price of a Stress token?

Yep, that's how those cards interact.

As mentioned, using Lando is using an Action from an upgrade card. Perfectly legal for EI and it doesn't interfere with the Focus Action either although both could yield similar results.

The Lando Calrissian card starts with the Action: header, so it's all good from there. Any upgrade card with the Action: header is a possibility for Experimental Interface. You cannot use an upgrade that doesn't have the Action: header even if it grants you an action or free action.