About ten years ago, it was considered a mistake to have printed the Titans in both M11 and M12 since players got annoyed about having them in Standard for so long. With the three year Standard, that increases the risk of having cards that wouldn't be banned in a two-year Standard sticking around long enough to bother players. Is this influencing what sorts of designs are in upcoming sets?

It’s something we think about. Note that the power level is higher for three-year Standard than two-year Standard.

Do you think we could get more cycles like the Kaldra pieces and the empires cycle from M12. I know I personally love them and wouldn't mind seeing them more often.

The lack of blocks makes it trickier, but not impossible.

Are we going to see more Mind Control variants at uncommon like Lay Claim in the future? This is the first one since Magic 2012.

The default for permanent stealing is rare, but obvious we occasionally veer away from the default. I wouldn’t expect it to happen often.

When you need a certain functionality that already exists on a card, how do you decide which cards will get reprinted (such as Curiosity in Innistrad) and which will get functional reprints (such as Pharika's Cure in Theros as opposed to Sorin's Thirst in Magic 2012)?

The creative team usually decides whether a reprint is the same or gets a new creative skinning. The two big exceptions is when we think the card returning is exciting and we want it to be the same and when development doesn’t want eight of a certain card in a certain format.

With Magic 2012 and Innistrad-block, Hexproof became a common ability. WIth Magic 2013 and Return to Ravnica, hexproof stepped back. Did you get negative response concerning Hexproof? Noone I know really likes it.

The scaling back is in response to the public outcry. Believe it or not, we do actually listen to what our players say. : )

You expressed affection for some of the guild keywords. What was the reason you scrapped them all?

We haven’t scrapped them. Bloodthirst, for example, was just used in Magic 2012. We’ve chosen to make new keywords for the guilds because one of the joys of Magic is exploration and discovering new things.
Ten keywords is a lot though so we opted to make space for them by not bringing back any of the old guild keywords.
Note that one of our design constraints was to make sure if you shuffled a bunch of cards with the same guild watermark, despite where the cards came from, the deck would feel and play right.

So far we haven't seen any common artifacts in M13 and Magic 2012 had, to my knowledge, only a single common artifact (Manalith) is this a deliberate trend with core sets or a part of new world order?

Artifacts since the beginning were not meant to be all that common. Yes, we’ll do a few at common in some sets, but unless the set has an artifact theme, we tend not to have too many common artifacts.

I'm a big fan of the Star format for Magic. Do you think Wizards will ever formally recognize that format with a separate expansion, as it did with Commander? I notice there are a few enemy colour targeting spells (Deathmark, Combust, Flashfreeze etc), at least one for each colour, in Magic 2012. They don't seem to be too popular or useful... But they're great for making decks for a Star game.

I have no answer for your question because it’s an area outside of my expertise, but you have a tenacity that is admirable. Since I doubt anyone but me knows this, dcconquist has been asking this question for what I think is weeks (or maybe it just feels that way. :) ) I think the biggest strike against the format is that it requires exactly five players which makes it a bit restrictive.  I just felt like you deserved an answer for sticking with it.

So I just got a bunch of new players into the game. Right now I run Theme Deck tournaments at my townhouse to make sure everyone stays on equal grounds and my friends don't get discouraged. What would be the best way to eaaaase them into constructed or another easy format? I don't want to scare them off from the game too quickly...

Minimasters are a fun format that’s very easy to pick up. Shuffle three of each basic land into a booster (I’d start with a core set like Magic 2012) and play.  By the way, Magic Celebration on September 10 is going to be running free minimaster tournaments for all attendees.