I'm not blaming those on duty, other than from the videos the compliance and maybe allowing selfies with these terrorists wasn't the best of ideas. The major questions have not been answered and as for the last one, with proper preparation, you've seen the armed guard that was there for the BLM protest, the end result would have been totally different and they wouldn't have been so badly outnumbered and outgunned! Can't remember ever hearing of a US government building being outgunned by a protest! And this was the Capitol building for **** sake!
One point I'll keep to bring up is that all it takes is for one of them to have been carrying a bomb, be that one of the good ol boys or someone infiltrating the group for their own means, it would have been extremely easy to do and the security have to prepare for that possibility