...do they ever actually explore the space station in any of the books?
That space station features prominently in one of the early Outlanders books, but to date I don't recall the companions in Deathlands ever returning there.
How many (long series) are there?
The Baronies Trilogy (books 46-48)
The Skydark Chronicles (books 53-55)
The Illuminated Ones (books 59-60)
Altered States (books 71-72)
The Coldfire Project (books 75-76)
Empire of Xibalba (books 84-85)
There is also a loose trilogy of books spread out over several years: Shadow World (book 49), Breakthrough (book 57), and Doom Helix (book 94).
The only other close thing I can think of is the direct crossover between Deathlands: Shaking Earth (book 68) and Outlanders: Sun Lord.
Does anyone like dean?
He's annoying as a child. He's awesome in Prodigal's Return (book 100).
"Sadly then I knew the answer. All her life she was a dancer, but no one ever played the song she knew." - The Residents