Hi there and welcome to planeshift!

About your questions. As such there will be no \"final release\" as PS is and will remain in a constant state of development until the devs decide to shut the project down (God forbid). But referring to your questions:
1. The world will be pretty much limitless. Currently the only plane of existence is Yliakum, a giant hollow stalagtite with eight different steps, or levels. The current town (Hydlaa Plaza) is but a mere fragment of a city on the first level. Also, the name of Planeshift itself is just that; Planeshifting, travelling to new planes (A Universe is not enough). So as you can imagine, it will be pretty big

2. I would say that
most houses and buildings will be enterable. I suppose there would still be some which remain only as eyecandy.
3. This is already implemented, but skills and money aren\'t, so it doesn\'t work. Future releases will see tutors, who will be able to raise your skills in exchange for money.
4. Yes, but don\'t hold your breath for this one. You\'ll probably be able to tame Pterosaurs and Megaras, so I do not see why you cannot tame monsters.
Please understand that these answers might not be 100% accurate, and are hard to answer as they are mostly features that will appear in the distant future (some say after armageddon).