I'm not sure if I would vote for any of the options as they are currently described.
Era/Theme: there aren't enough era-specific weapons for each perk to make this worthwhile. The only perks that have Tier 1 weapons appropriate for the Wild West are Slingers and Sharps. The only perks that have T1 weapons for the other eras are... well... none. T2+ weapons would have to be dumbed down to begin any other era/theme.
If minor tweaks to weapons are necessary anyway, then tweaking some re-skinned/remodeled current weapons with tweaked stats would make this outbreak option more feasible. For example, remodeling the Tommy Gun to look like the PPSh suddenly makes it a PPSh. Make the 1894 look like a De Lisle and use the Mac 10 shot SFX and you're all set. Seems easy enough to me, but I used to do web development and am aware that a client's suggestions might be more difficult than how they are imagined.
If I think of this outbreak as similar to Coliseum, where each era/theme is limited to one or two perks, then it makes more sense, but I'm not a huge fan of Coliseum for that exact reason and I still don't see any WW1, WW2, Vietnam, etc era options.
Perk Roulette: swapping? Gotta be very careful with that. I share
@Sarcy's concerns. Some troll will invariably drop all their weapons just prior to going into the Boss Round, leaving their teammate to inherit just a gun and knife. Auto-selling weapons prior to perk swaps will help prevent trolls, but I'd still prefer no weapon swaps whatsoever. I'd rather there be complete randomness.
Secondly, changing perks between rounds intrigues me, but needs to come with some form of economic equalization. Demos are notoriously broke after the first wave while level 20 SWATs start, given the appropriate perk skill selections, 375 dosh richer than their friends. Medics can get financially stuck on the SMG. I would like to see any perk change occur immediately at the end of each round so that players can buy/sell weapons prior to the next round. Also, giving every player the average of all dosh earned will give every player a chance to buy appropriate weapons each round.
Thick Skulls: I like this well enough because I agree that a lot of players are too caught up on aiming for the head, but am not sure why we need an outbreak for it. I can choose to not aim for the skull whenever I want. I'm not against it at all; not excited by it either.
Speed Changes: I share
@Sarcy's concerns and also question how it would play out in solo play. I might need to try it before judging it. Seems like great practice for Sharps.