1. Can Sith be Light sided(lore wise)? Sth like crazy vigilantes? I know that it'd be Nerdy not to 11 but to 111, but is it possible? I see ABSOLUTELY NO reason why not. If jedi can be dark...
2. A question about the movies that always interested me: how was Darth Maul able to be an apprentice of Darth Sidious? I mean they are both Darths. Shouldn't Maul had been a Lord or sth? It just stinks of error within hierarchy to me.
3. Is Empire the best Faction or what?
Light Side sith? Ehhhh, this one's tough. Embracing the sith code definitely predisposes a person to allowing their emotions and whims dictate their actions. Is it possible? Not exactly. One's interpretation of the sith code may lead them to believe the dark side is a slippery slope causing the reckless to be ruled by and slaves to their emotions and impulses. However, by definition the dark side is viewed as the freedom to act on and embrace one's emotions and passion, rather than bottling them up and stifling them.
The Sith embrace this code, claiming the freedom to exhibit and act on one's emotions, feelings, and impulses sets them free. Many of them believe the Jedi to be repressed fools. But on the flip side, many Sith are extremists who are in fact ruled by the very thing they claim gives them strength and freedom. Their crippling lack of impulse control and need for instant gratification causes a self-perpetuating and never-ending cycle of power struggle and fear. The more perceptive sith who see the bigger picture likely do not fall prey to such pettiness, but they also likely do not look too favorably on the repressed, held-back, heavily restrained life of the Jedi.
The Sith and the Jedi are extremists. A Sith cannot be on both sides of the spectrum at once, though many Sith and Jedi likely fall somewhere in the middle and even cross the line now and then. But the traditional Sith archtype not only embraces the Dark Side, it spurns the Light Side. Remember, also, that most of these people are born and raised in Imperial space (in this era at least), and grow up witnessing the power struggles within its own government, how might makes right, and watching the Republic vs Sith dynamics. They're predisposed to equate the Dark Side with power, they see it every day, so convincing a sith otherwise is probably quite the undertaking, perhaps even futile.
As for Maul and Sidious, they live in a different time hundreds of years in the future. TOR takes place in the distant past. Times were different.
As for which side is better, it's all a matter of perspective. I personally prefer empire from a roleplay and lore standpoint but if I had to choose one of the two governments to actually live under I would prefer to live in the republic.