Nothing confirmed yet for Cocoon - you might need to wait until after Miami is done with. If last year is anything to go by than that would indicate Cocoon opening is likely for that date.
Be wary though, as previous years it has been a week later. Just keep checking back on these forums & the spotlight calendar - once confirmed it'll be added almost instantly!
Regarding your question about tickets: the answer will vary depending on which forum member you speak to.
DC10 can only be bought in advance through RA, and it'll be limited so will sell out fast. However... there's no real incentive to do this as: a) you won't save any money, pre-sale / on the door are the same price, and b) it's one of their quieter dates, so no chance of being a sell-out.
In regards to Cocoon - you will save a bit buying from Spotlight in advance. Maybe as much as €10. You'll certainly pay more on the door than buying in advance in any case. Benefits of buying through spotlight: hassle free cancellation and full refund up to 24hrs before the event - in case you experience a set-back or have a change of plan.
Negatives (if you can call them that) - you'll need to carry ID and match the name on the ticket, which some ppl understandably don't like.
Some pre-sales come with time limit restriction ie. you must arrive before a deadline. But I'm fairly certain this does not apply to Cocoon at Amnesia
