1) You can absolutely play without a dedicated Dealer! It really depends on your playgroup, I think: in my experience playtesting, some groups really benefit from having a single player representing the Opposition to keep the action and moving, while others can totally do as you suggest and just come up with what the Opposition does as a group.
2) The Weirdo's Jack ability is pretty strange, right? You've got the rules all correct, but there's a fun unstated benefit that comes from swapping your Heat with the Deck: you know exactly which cards are in the Deck now! This is usually best if you've got 4 or more cards in your Heat (a bit rare but certainly not impossible), because you'll get dealt 1 card for the Hit and then 2 more for your new Heat after, but that means that you know exactly what cards are in the Deck and can plan around it for future Hits.
Basically, it's the Weirdo's roundabout way of stacking the Deck!
(There's an unstated assumption that if the Deck ever runs out, you just shuffle up the discard and keep dealing; that's a good note for me to explicitly to the FAQ, thanks!)