The best practice is to have a webpage dedicated to each podcast, something like https://www.YOURBRAND.com/YOUR_PODCAST_podcast. where you have an embed player with the podcast, a badge to apple, spotify, google, etc., and each episode is there as blog post, including show notes, transcriptions and resources (link to books, guests contacts, etc).
It is better to direct to your own site rather than to the hosting service, as not only you increase traffic, but can monitor and measure overall results from facebook/LinkedIn/etc campaigns.
It is also a place to open a communication channel for listeners, so they can send comments and questions (if you open a contact section). what are your thoughts about it?
The best way is to make a top-quality show. Make it so good that people can’t help but share it with their friends. Word of mouth advertising is 100x more powerful than ads, and it’s free. You’ve just got to earn it.
There’s no perfect length. Plan and tell your story, and however long it ends up, that’s how long it needs to be.