1. Can you own a house is it instanced? Or is it out where everyone can see it?
2. Can you have pets? Do they have to eat to live? If they die are they perma-dead, or can you rez them? Can you ride these pets?
3. Is there item durability? If there is, can items be repaired as many times as you wish?
4. Can your avatar learn skills from other classes? If so, can you learn all of the other classes skills, or is it limited?
5. Is the movement click-to-move. Or is it WASD based? Looks like it is click to move - cool!
6. Is there an off-line messaging system (e.g. a post office to send messages and items to offline players)?
7. Is there a bank or warehouse? Is it shared among all of your avatars on a server?
8. Does your avatar need to eat to live (other that healing potions in battle)?
9. Is there an Auction House, or some other method for selling items to other players when you are offline? How many days can you leave items in the auction house?
10. Is it possible to gimp your character? For example, in Maplestory, you can easily mess up your HP build if you don't put points in certain skills at certain levels. Is Mythos like this at all? (I hope not).

OK - it's in closed beta and they just radically changed the game play with the content on the test center (the stuff that hasn't even hit the general beta server yet).  Things may continue to change drastically.  First, please note that this is designed to be a casual gamer's MMO - it's not trying to compete with WoW.  That being said, I'll try to answer your specific questions for the game as it exists today:

1. No houses at all- maybe in the future.
2. You have  rudimentary minions that do things like attack mobs for  you, but you don't control them, feed them or repair them.
3. No durability, no repairs
4. No - you're locked into a skill tree
5. Both click-to-move and WASD, but the WASD kind of sucks right now as does the follow camera.  The camera is being completely reworked. It is beta, expect it to get better.
6. Yes - you can mail other players, even if they're offline.  Right now, you're limited to sending items to players of the same time (normal, hardcore and elite) .  The devs are considering allowing trading between normal and elite players, though.
7. Bank yes, shared no.
8. No eating/drinking
9. No auction house - someday there will be...
10. Yes - you can totally gimp your character,  especially since you're locked into skill trees, but you can respec, reset crafting skills, etc...

~Ripper