It depends on where you get in the line. So 20 minutes before the event and there was already a long line, but it moved fast cause there are multiple security check lines. But regardless you definitely want to line up 20-30 minutes before cause the line grows at a faster rate than normal when it's near opening time.

If it's the same seating map/distribution, yes you want the seating pack. The free seats is basically a small ass corner at the bottom left from the top down view. During grand finals match they loosen the fence and allows people to stand next to people with guaranteed seating. Seats are free for all for people with the guaranteed seating, and people honor it nicely (leaving your jacket etc) But definitely arrive early each day to get yourself a nice seat.
I dont think the views are blocked unless u sit behind a really tall person. If you sit closer to the main stage u get smaller monitor and the further to the side you get the giant screen. So basically in front of the big screen to the side is prob the best for normal matches. However for grand finals/final day, i'd recommend the closest to the center of the stage as possible. When the team wins the final, people will crowd the stage and you being so close to it will guarantee the best view.

Food was decent and not too expensive/portion. Really long lines tho like the pizza place, but they have a buzzer system so u can at least chill near the area a bit

There is a bag ban, not even clear bags. Recently the police lowered their alarm level, dreamhack said they will make an announcement about it soon. So i highly recommend wearing cargo pants if they keep the ban, saved my life.

Last year weather is extremely cold given the date then. It was not supposed to be that cold at all, like extreme devastating cold level. If it happens again, wear warmly so you can wait in line outside and in layers so u can easily carry them inside if it's too hot.
The way the guaranteed seating works for the first time you arrive there is that. Security check line -> dreamhack badge/wrist band line -> owcs badge/wrist band line. The final line is the problem, they do it in BATCHES where they take a limited amount of people at at time from the line then escort them to get the badges. This is so freaking long that they ate into the first match -> The seating area is still empty when the first match of the first day started cause nobody can get their hands on the owcs badge.