1) Can I shoot with one weapon and reload in the same turn?
I need 2 turns to fully reload a flintlock gun and according to this answer I can make a non-roll action with an (optional?) -2 penality Agility check.
Core rules manager Clint Black gave an official response clarifying this. If it is a weapon that only takes one round to reload, then you can shoot (with a -2 multi-action penalty) and reload in the same turn, although the GM may choose to require an Agility (-2) check if they feel like it would be difficult to do both in one turn. As for weapons with Reload 2:
A character couldn't reload a weapon with a Reload of 2 and fire at a -4 penalty. That would be duplicating the same action, reloading, in one round.
So they would reload on one round, and then could finish reloading and fire on the next round at -2.
As for the Agility roll, that's optional and only if the GM feels it's difficult to pull it off in one turn.
2) Is this round sequence correct (and possible)?
I'll break this down into steps:
- Round 1 -> Shoot with gun 1 and gun 2 (without any penalty)
Because of you said your character could do this (I'm guessing Two-Fisted and Ambidextrous Edges), yes you can do this.
- Round 2 -> Reload with gun 1 (I can't reload two times, right?)
Correct, you can't reload twice in the same round, per Clint's ruling in question 1.
- Round 3 -> Reload with gun 1
Fine, although it is possible to shoot with a multi-action penalty.
- Round 4 -> Shoot with gun 1 (wihout penalty?) and reload with gun 2
Shooting with gun 1 would be at a multi-action penalty (so -2 penalty). Also, I would personally as a GM require an Agility (-2) roll for reloading gun 2 because reloading a black powder weapon while you have gun 1 in your other hand seems to be pretty difficult.
This applies to rounds 5 and 6.
3) Is there something which allows me to shorten reload times
In core Savage Worlds, no. Deadlands Reloaded has the "Speed Load" Edge that allows you to reload as a free action (or reduce the number of rounds by 1 for weapons that require multiple rounds to reload), but unless you are a playing in that setting, you can't use it.
4) Can I hold a rifle and a gun at the same time?
Wibbs clarified this in the comments:
Yes you can hold them both. You can only use each hand once in a turn, so you could fire the pistol with one hand, and the rifle with the other (-4 penalty for firing a two-handed weapon with one hand). You can't fire the rifle with two hands, as one of them is being used to fire the pistol. The -4 penalty to firing is a standard rule that has been confirmed by Clint a number of times. It derives from the penalty you get with the One-Arm hindrance.
So yes, but your rifle is at a -4 penalty (the same as if you had the One-Arm Hindrance and were firing with just one arm).