My question here, is this forum open for everyone?
The forum is opened for everyone who will abide by the rules. Is every board on the forum opened to everyone? No. There are some boards that unless you are a mod/staff you can have access to it. Well, in reality, those boards are just for administrative stuff so, nothing to worry much about.
Can I also discuss or post about bitcoin and crypto like others?
Yes, again you can. But I strongly advised beginners to read more first, than to be in a hurry to make a post. Because it is always likely that whatever question they may have to ask has already been answered. The only exception is when there is a more recent information or unique angle to it.
This is a misconception for every beginner that since they are in the forum, they are actually obliged to post immediately. But in reality, no one is forcing them to post, they can just read the threads in the forum all they want and don’t react or reply on it.
However, it’s still a different feeling when you join in the discussion, especially if your are well knowledgeable on the topic. You could have shared your valuable insights, and let the other members benefit from it, just like you benefit from their informative posts.