Who Would Win: A Hollywood Film vs One Historically Uninformed College Kid

I had several questions while watching the 2004 film King Arthur. About twenty minutes into the film, I thought, "Wait a minute, didn't the Roman empire fall by now? Didn't the so-called Dark Ages happen after the Roman empire fall?" Either way, they’re there, and as far as I know, their soldiers are dressed as they would have been historically. I have no clue how they did with the Saxons on the historical accuracy front, but for practical reasons I wonder about the Saxons’ loose hair. It makes them look cool, but if they’re constantly itching for a fight, shouldn’t they tie it back or cut it short? Then there are the Woads. Are the Woads the same as the Celts? If so, then as far as I know, the film’s depiction is historically accurate (blue body paint, questionable leather armor, both men and women in combat), though I still wonder how they managed not to get stabbed more often without a lot of protection during battle.

Regarding Arthur and his knights, I was surprised they let Guinevere be one of their archers. They’re Roman-trained, so shouldn’t they balk at women who want to fight? “A woman? Fighting alongside us? Does she think we’re Woads?” Speaking of Guin, when she first showed up in her archery outfit, I thought, “elf.” That flowing dress/robe could get caught on something, and I don’t know where or how she got all that fabric. Wouldn’t it have been expensive to get that much? Either way, said fabric looks too light for winter. Later she adds a cloak, but she still could be warmer, and maybe have armor. At least she eventually ties her hair back for battle. Also, I doubt hygiene, nutrition, and cosmetics back then were advanced enough to make anyone as pretty as Guinevere and Alecto.

Another question: did Briton brides dress like that? The white dress and veil are traditional for us today, but was it for them? Or are those traditions more recent and from elsewhere? Also, again: where and how did they get all that fabric?

"Go all out. It's my wedding." -Guinevere, probably

Image from Harvey Furnishing's web site.