Depends what type of ticket you are on about really, same for any of the well supported German big boys standing are hard to get.
Have sat and stood at Schalke, stood 18 month ago in the cup midweek - just got lucky by picking one up through official site for 15 euros. Otherwise seated is pretty easy to get for 9/10 of their matches, same for most Bundesliga matches - the standing tickets are the ones that are hard to come by for face value if you are just a general buyer.
Standing at German football is a must personally, done 40 plus of the Stadiums in the top 3 divisions now and wouldn’t return to any to sit to be honest.
Auf Schalke is their fan pub on way to stadium, can’t miss it off the tram/u bang whatever. Also in the standing area there is a bar with a fair bit of memorabilia. Neither Dortmund or Gelsenkirchen are great drinking places really, Bochum is mind and the Club has a few ties with Rangers - Bermuda Triangle area is a laugh.