When you talk Thranduil questioning Thorin, are you sure you're remembering the book and not the movie? Movie Thranduil was a dick to pretty much everyone, but book Thranduil was trying to find out why the dwarves and spiders disrupted his people multiple times, and got no answer to the question 'what brought you into the forest in the first place?' Yes, he's suspicious, but given the chain of events - and Sauron just to his south - he pretty much has to be. He and his kingdom are on constant guard. And when given a chance to explain, Thorin didn't. He gave a more informative answer to the Great Goblin! (I'm at a loss why he didn't just tell Thranduil the same thing he gave the Great Goblin - "going to visit relatives". It would have been both reasonable and acceptable to Thranduil, given Dain is in the Iron Hills. I get Thorin being cranky, but "We were trying to cross Mirkwood and lost our way and our supplies, thus the wandering around starving!" is a lot more likely to allay Thranduil's suspicions and maybe get some help than "We were starving, why are you so mad we killed your spiders?" Well, at a loss aside from the obvious - Thorin defusing the situation himself would have deprived Bilbo of a chance to shine...)

But yeah, we're going in circles. I also feel like in your pro-dwarf fervor, you're overlooking my (admittedly only stated once) reason for why I believe Thorin was unreasonable. Given what we're told about the effects of dragon gold (and looking at its observable effects on a character previously established to be a good or at absolute least competent leader, I'd say 'dragon sickness' is probably a better way to refer to it), I question whether Thorin was in his right mind for much of the time from regaining the Mountain until some point during/immediately after the Battle of Five Armies. What's more, I can't find anything in the text to indicate that Thorin knew that such an effect was possible - while the narrator is aware that dragon gold can do funny things to people, Gandalf never warned anyone about it. So I see Thorin being caught unaware by what is essentially a mental assault he didn't know he needed to guard against. (He also had no one around him who could have realized what was happening- if Thorin didn't know about dragon sickness, it's unlikely the rest of the dwarves did either; Bilbo recognized that something was not quite right but didn't have sufficient knowledge of dragon lore to identify what that 'something' might be.)

Orc killing? I hope you're not expecting any movie!Legolas-like defiance of the laws of physics. (Are there rules to the competition?)