I'm planning to have my players visit the graveyard. The remains of Alderaan to scavenge whatever they can find.

From Wookieepedia:

Many Alderaanian Exiles performed a private ceremony called the Returning, and would shoot capsules filled with gifts for their friends and family. Some Alderaanians, who called themselves the Guardians, took to patrolling the Graveyard to prevent pirates from stealing the capsules.

but:

Imperial agents often lay in wait for ships performing a Returning ritual. They boarded the ships and arrested the passengers and crew.

What other challenges could they run into apart from the Guardians and Imperial agents.

I'm thinking asteroids of course. Giving setback on all pilot checks. And maybe upgrade the checks once if they choose to fly closer to the asteroids to stay more hidden.

They might meet other pirates.What else?

And what could they find among the remnants of Alderaan?

Mynocks!

Force ghosts, perhaps?

A big vein of ore with some mysterious properties. It's incredibly dense, or gives off its own light, or has weird a magnetic signature, or is nearly indestructible, or is made from highly costly material that is never found in this great a quantity. Whatever it is, it's just a bit too big to fit in their cargo hold, but they can try towing it somehow.

Crashed/derelict ships.

Ruins of Alderaan cities and eerie signals that appear to indicate someone survived Alderaan's destruction and is trapped inside a sealed building with limited supplies...

1) Actually a still working transmitter that's sending out the last message by a long dead family

2) A decoy arranged by pirates to draw rescuers into a trap using a field effect similar to the one used to seal off the world with the Blue Shadow Virus cure from the Clone Wars animated series.

3) A damaged Venator starship whose shields was on when Alderaan was hit, disabled they're desperately trying to contact help but its going to take a miracle... (Oh look was that Princess Leia in an X-Wing ... hey why she's heading to the other Venator starship? )

4) They're actually Imperial and were unable to get clear before Alderaan was blown up...

5) Unknown to anyone deep within Alderaan was some ancient sealed vaults, now that the worlds been blown up its actually possible to get inside one of them... now if only they could find one with a working life support... oh well space suits and rebreathers will have to do!

6) Would make a good place to hide an Imperial research facility wouldn't it?

Oh please - go get thyself a copy of The Graveyard of Alderaan and check that out!