My boarding group wasn't last, but was near the middle. Not sure how they knew (notes in the computer?) but the gate agent knew I was on my way to an interview, and was not surprised when I asked if it would be ok to hop on early to say hi to the crew. Both pilots and FAs seem happy to chat with me, wished me luck, and FAs said I could sit anywhere except exit rows.

I was following advice to introduce myself to the crew upon boarding, and in my experience that has been easier to do during pre-boarding, which is why I asked about that. On the other hand, on my flight back everyone looked super busy so I didn't even ask and boarded with my group. So, judgement call on if/when to introduce yourself to the crew as an interview candidate.

The 2 restrictions I've usually heard from SWA FAs when jumpseating are to sit anywhere except exit rows or first 4-5 rows. Everywhere else is fine. I was also told that when boarding with any normal boarding pass (ie. not jumpseating) and not pre-boarding, then any seat still open when you get on the plane is fair game since passengers who paid extra to board early will already have chosen their preferred seats.

I haven't yet been told "official" company policy or procedure for this stuff, this is just what I've seen or been told during several JS flights and my interview trip out and back.