Are there any smoke grenades? I can't seem to find any.

If you have accurate and inaccurate on a weapon do they cancel out or do you roll both dice?

Thanks

Roll both the boost and setback dice.

(Then get a Custom Grip added to it, because it cancels one setback die.)

No gas grenade, but there is a poison gas grenade. It's got N/A for both damage and critical, deals a dose of poison to the target, and has Blast 2. The smoke lasts for 5 rounds indoors, 2 rounds outside. It costs 50 credits and has a rarity of 5. For a smoke grenade, I would drop the rarity to 3. Rather than it delivering poison, I would give it Disorient 2 and leave everything else the same.

Coyote6 is correct: by RAW you roll both, but I have seen GMs house rule that they cancel out, myself among them.

Adding a Blue and a Black die (or precisely, X Blue and X Black dice) to a roll slightly decreases the chance of a successful roll (on the order of a couple percent for 1 Black + 1 Blue).* But, it increases the chance of and number of advantages, because a Blue die has 2 faces with a success, 2 with a advantage and 1 with two advantages, while a Black die has 2 faces with a failure, and 2 with a threat.**

*This result is due to the asymmetry of the success system in SWRPG - you need a net success to complete your action, so adding more dice that have the same probabilities of success and failure center the pool around 0 net successes more strongly. It should matter more when the chance of a success is closer to the probabilitistic knife's edge anyway.

**Basically, a Black die has 2 faces with exactly one threat, and 2 faces with exactly one failure. The Blue die, in effect, adds an advantage to one of the faces which already has one advantage and also to one of the faces that already has a success.