Would you pls explain about my questions on the script of the movie "Toy story3"?

In this cut of movie "Toy Story3"
I got some questions on the script below.
I don'k know what these parts mean exactly.
i'd like to get your explanation about them.

-1st question: Hold him steady
( Does this mean that Woody(=sheriff) wants her(=Jessie) to make the horse(=him) run the same speed to balance a even level and not to shake
for sheriff to get on the train well)
- I wish you could understand my point, then I think my sentence of question is a little bit wrong , How can i put it on the right?

-2th one: -To Infinity... And Beyond!
Why did Buzz(=space ranger) speak like that? I can't see why he speak "To Infinity and beyond".

*Movie cut link:
http://tvpot.daum.net/clip/ClipView.do?clipid=45000301&rtes=y

Script goes like:
-------------------------------------------------

-Ha! Ha! Ha! Money, money, money!
-Hey!
You got a date with justice, One-Eyed Bart!
-Too bad, Sheriff -- I’m a married man.
-Ai! Ai-ai-ai-ai-ai-yah!
-One-Eyed Betty!
-Whoa, whoa... Ahhh...!

-I believe you dropped something,Mister!
-Jessie?!
-Give it up,Bart.
You’ve reached the end of the line, Bart.
-I always wanted to go out with a bang!

-Oh no!
-The orphans!
-Hate to leave early, but our ride is here.
-Oooooooooo!
-It’s me or the kiddies, Sheriff!
Take your pick!
-Ride like the wind, Bullseye!
-Hold him steady...

-Woody, hurry!

-No...!
-Glad I could catch the train!
-Now let’s catch some criminals!
-To Infinity... And Beyond!

-OooOOOOoooo!
-Reach for the sky!
-You can’t touch me, Sheriff!
I brought my attack dog with a built-in force field!
-Well, I brought my dinosaur, who eats force-field dogs!
-Yo-Dee-Le-Hi-HoooOOOOOOOO!

-Evil Dr. Porkchop!!!
-That’s Mr. Evil Dr. Porkchop to you!!