TheSagaContinues

I was wondering if you can combine those two talents.

Call Weapon let's you draw and ignite a lightsaber as a free action. So, is it possible to have your lightsaber on your belt or the floor or whatever, use Call Weapon as a free action and then Block as a reaction?

You can do free actions when it's not your turn, but not directly in response to someone's action (which would be a reaction).  I'd say that free actions happen between other people's actions or turns.

Let's look at Second Wind.  Soldiers have a talent called Hard Target (reaction to use Second Wind in response to an enemy's attack).  Pretty simple.  But with the Fast Surge feat (take Second Wind as free action), you would need to do it at a time when it wouldn't be a reaction (enemy 1 ends his turn, you take Second Wind as free, enemy 2 goes).

You would probably be able to Call Weapon between an enemy's actions (he uses a move action to get near you, then you Call Weapon as a free, then he attacks with standard), but not directly in response to an attack like Hawk-bat Swoop or Unhindered Charge.

Mechanically, what others have said makes a lot of sense. On the other hand, this very thing happened in the final fight between Anakin and Obi-Wan at the end of Epsiode 3. Both of them dropped their lightsabers. Then Obi-wan called his weapon to his hand and attacked Anakin who was lying on his back. Anakin called his lightsaber to his hand and immediately blocked Obi-Wan's attack:

skip to 1:29 in the video for the scene in question

-skip to 1:29 in the video for the scene in question

Usually in a situation like that I'd say Kenobi's unarmed attack + retrieving his saber ends his turn, Anakin retrieving his saber starts his turn... then maybe Kenobi spends a DP to go ahead and attack while Anakin is still prone. It's feasible, especially considering the fight wasn't coreographed with Saga rules in mind.

What? that's crazy talk! Episode III was obviously choreographed with Saga in mind. Lucas insisted on it. I'd also like to say that Kenobi's attack looked more like an AoO (from say Counterpunch) than his own turn. In that video I'd be inclined to agree that Anakin retrieved his saber in response to Kenobi's attack. And personally I'd allow Call Weapon to be used to enable a block, mainly because it sounds awesome and it could really go either way.