Keep it Classy on LinkedIn
I think your first instinct regarding #1 is spot on. I don’t like it either – it feels phony, presumptuous, and doesn’t buy you dick. Anyone can be an “interviewee” (and we all know it) so it won’t “boost street cred” or entice other firms to approach you. You know what DOES entice other firms to approach you? Developing a reputation for being a kick-ass, revenue-generating high performer and not some douche who posts a bunch of bullshit on LinkedIn.
But your second observation is interesting, and this one I like. I’d suggest going one better than simply tagging the company - use the post to connect with and then call out all the people you’ve met - your future boss, the HR person, etc. and mention how much you’re looking forward to working with them. Kinda like a public “thank you note.” You’ll be strengthening relationships before you even walk through the door (more class, less douche).
People do a lot of crazy shit on social media these days, and senior level decision-makers don’t fall for the majority of the nonsense. Make sure you don’t either.