Jolt to a stop

[Akebono]

In chapter 1 of "Origin" by Dan Brown, Professor Langdon arrives at the Guggenheim Museum Bilbao
and goes down the irregular steps. After that sentences below follow:

At the bottom of the stairs, Langdon jolted to a stop, staring at a massive object that loomed ahead.
Now I've seen it all.

And my questions:

1. How did Mr. Langdon look like precisely, when he "jolted to a stop"?
According to dictionaries in the internet, "jolt to a stop" means "stop moving suddenly which causes a jolt".
Did he stumble then?

2. Does "Now I've seen it all." mean something like "I'm so astonished"?

As a non-native speaker of English I'd be most grateful, if you could take time to answer my questions. Many thanks.

 

[Rover_KE]

Welcome to the forum, Akebono.

1. We can only guess how he looked—shocked? surprised? There is nothing to say he stumbled.

2. Yes.

 

[jutfrank]

He saw something that astonished him.

 

[GoesStation]

He stopped suddenly. Someone watching would have been surprised by the abruptness.