Podcast lengths vary, obv, but the ones I listen to the most are around an hour long. If the content is good the time flies by. This gives you time to have those multiple segments in each episode. Some folks like shorter listens due to not really liking any type of talk radio but all of the big ones I subscribe to stay right around that hour mark.
I think your content ideas are great. Weekly guests may or may not be a problem but I wouldn't promise one every week just in case something happens where that person can't show up or call in or whatever.
Our tiny little podcast is just comedy based BS. We aren't big, have done 13 episodes, but we're starting to get a feel for it. I found out today we've got, like, 13 listeners in Ireland, 8 in Sweden, and 5 in the UK apparently. LOL Never know who will listen so just focus on content ideas and let the convo flow naturally.
What kind of equipment and hosting are you thinking of using? I recommend Podbean. From there it can cast out to Spotify, iTunes, Google Play, etc. It's silly cheap and fully customizable as well.
Here's ours for an idea:
https://buckhornpodcast.podbean.com/
It's totally free for listeners to sign up, subscribe, leave comments, etc.
I'd also recommend checking out The Joe Rogan Experience and The Last Podcast on the Left for some good ideas.