I'm planning my first session and I'd like to include the three basic encounter types combat, a chase, and a skill challenge, followed by a starship encounter but I'm not sure what to expect from the players.

The players will have to steal a YT-2400 and burn atmosphere to get out of Nar Shaddaa safely but not before a spectacular starship scene.

Not only can I not figure out who regulates space around Nar Shaddaa/ Nal Hutta, I'm not sure how they prevent people from jumping into Hyperspace (not that I'm opposed to that.) I'm also not sure how much to throw at them safely either.

How do I make this fun?

If they're trying to escape somewhere, use chase rules as a start.

Next, Hutts control Nar Shaddaa. So the people chasing them could be anything from thugs in Z-95s payed for by a crimelord, to hired security goons from a "legitimate" company hired through a shell corp by a crimelord, to actual Hutt security forces that work directly for a crimelord.

So, you have to leave a planet's gravity well to jump to hyperspace, which as a moon, Nar Shaddaa's well isn't too big, but it's right next to Nal Hutta, so you could just say they have to escape Nal Hutta's as well. The core rules call out 5-15 minutes to reach a safe hyperspace jump point when leaving a gravity well. I would say that's 5 minutes at speed 3-4 and 15 minutes at speed 1. So they stop people from entering hyperspace by disabling their vessels before they get somewhere they can.

As for what to throw at them, using the beginner game as an example, the party escapes Tattooine in a YT-1300, and has to fend off 2-4 TIE fighters (based on whether or not they have 1 or 2 gunners). So I would say to pit the party against either 2-4 Z-95s or 3-5 Cloakshapes, or one Firespray, with a wingman or two in Z-95s or Cloakshapes, especially if all you have is the core book. Or a pair of Y-Wings, but those can be super dangerous with the best action economy in class, and torpedoes. If you have Lords of Nal Hutta, you could instead send up 3-5 Starhoppers after them, or maybe even one Krayt Gunship.

Also, to keep it fun, don't forget all the other space traffic. Use it as navigational hazards and such. There should be quite a few larger transports and shuttles clogging up the area.

Also, if the party does really well and disables there enemy, and gets that "Loot it!" mentality that you might not want them to have at this particular moment, flipping a destiny point to have more ships come after them is perfectly acceptable. Then again you could start the encounter telling them that they've got X on their tail, and Y and Z appear to be racing in from farther away, further enforcing that they get out as quick as possible.

I will respectfully disagree with Were above me on how many fighters he suggests your players to encounter upon their escape.

When my group started playing, they had a first session encounter with a group of 3 Cloakshape fighters which I had pitted against their Y-Wing and YT-1300. I have a pretty big group, we run anywhere from 5-7. On this occasion, we had 7. There was a Y-Wing who had an astromech player helping him pilot/gun, a pilot/copilot in the YT, and two gunners. Both of their ships took serious damage before the encounter was over and the players had managed a victory. They weren't being silly or reckless either.

Vehicular combat in any of the Core games for Star Wars *is* deadly. Keep this in mind. This has been an issue with the system since it first came to be. If you're going to have multiple ships engage your players, use minion rules to form a group of enemy ships (r if you have the Age of Rebellion Game Screen, the squad rules would work too). That's my suggestion.

The rest of Were's comment is spot on.