Should people place a reputation cap of ten before new users can answer a question? This would limit spammers tremendously. If not, should we wait until they have fully registered and block the e-mail from creating another account?
We already have a mechanism on the site for restricting users with less than 10 reputation from posting answers, called "protection". We use it solely for situations when there's a demonstrated need - a particular question that has attracted several answers from <10 reputation users that have been deleted. Users at 15000 reputation can also apply it manually but I recommend that we don't do it unless, well, something is demonstrated exceeding amounts of unnecessary attention through answers.
All users need to start somewhere, and answering is where many users begin their journey on a site on the network. We have no means to determine whether a new person is an expert who has wonderful advice to share, and someone with two cents they couldn't find a fountain for. Blocking the former from solving a question, be it an old one with a satisfactory solution or an unsolved problem fresh onto the site, is strictly harmful to both us (we lose an expert) and the user (they have a sour experience). For this reason, protection is pretty much strangleheld in its very niche purpose, and extended it sitewide would be disastrous.
We've been having some increases in spam activity on various sites on the network - the call-to-arms that users are using to clean up is helpful, and should we run into a flood as well then we should take similar action. We at Stack Exchange are also looking into more potent solutions to deal with spam, network-wide and otherwise. We should do something about spammers, I certainly agree, but we should do it in a means that doesn't interfere with our ability to welcome knowledge.
No. One of the design goals of Stack Exchange is to put as little friction as possible in the answering process. Requiring people to ask questions before they can answer them is counterintuitive, counterproductive and goes against most network principles.