Let's break this down.
1. Scanning tickets - Nope, he was a registered hotel guest. That would have made no difference because he didn't need to enter the hotel.
2. Multiple layers of security stations -- There were multiple layers of security stations. You couldn't just go straight from the hotel into the dinner, as the would-be assassin found out. And of course, that is a secret service issue.
3. Limited movement for hotel guests -- Of course there was limited movement. There were quasi-public areas (think hotel dining), semi-secured areas (think the press parties), and then hardened security areas (think the dining room where the WCHD was). Is your point that they should have treated the press parties as akin to the dinner, itself? What good would that have done in this particular case? The would-be shooter wasn't hanging out at press parties.
The simple fact is that when a hotel guest decides to sneak guns onto the property in his luggage and then his plan of attack is to simply run as fast as he can past security, there is not a lot you can do unless you inspect 100% of the luggage of the 2,200 guests at the hotel, which is not even one of your suggestions.