Hi Drees,
Let me try to answer all of those questions as much as I can.
Q; When will it be loaded?
A: I assume with loaded that you mean when it will be released? There are a few suspected release dates posted around the internet and they all say june - september 2015. (for example http://www.slideshare.net/openobject/keynote02). Odoo keeps talking about Q4 2015 though so expect it somewhere along oktober - december 2015.
Q: Are there many differences?
A: Yes there are quite a lot of differences. All the modules will be written in the V8 API instead of the V7. The modules will be fully responsive (see my answer about licensing) and will be made even more user friendly.You can see the official roadmap here:
http://www.slideshare.net/openobject/keynote02 The main roadmap for V9:
40% usability
20% Accounting
20% CMS / eCommerce
10% New design
10% Framework
Q: Is there a new API?
A: No there will not be a new API. There are currently two API versions, the API from Odoo V7 and the API from V8. All modules & code will be upgraded to the V8 API when Odoo 9 is released but you will still be able to use the V7 API.
Q: Is there a free version and what about licensening?
A: Besides of the Odoo 9 community edition (100% free) there will be a V9 Enterprise Edition. This is a pretty big game changer in Odoo 9 and directly stears Odoo from being fully open sourced to being partially open sourced and partially closed. The Enterprise Edition will contain a set of new apps on top of the Odoo community edition.
A good thing to know is that the Enterprise Edition will never be open-sourced and the code will only be available to official Odoo partners and Odoo itselfs. This also means that a non-official partner cannot sell the Enterprise Edition and thus an Odoo customer can only buy the Enterprise Version from Odoo or its partners. Another interesting fact is that the Enterprise Edition will contain full responsiveness! It will fully adapt itself to mobile, tablet, computer,.. and means that this will be the first Odoo version that is truely mobile useable.
If you would like to have access to these features you will need to buy the Enterprise version, which will be an additional 20€ per user per month.
The modules that we now know in Odoo 8 will remain available for anyone in V9, without any extra cost, and will always be publicly on Github. New apps that will be in the Enterprise contract are account_dashboard, account_check_print, web_mobile, project_forecast and probably a whole lot more that are not publicly discussed yet.
If you want to see exactly what will be in in the Community edition and what will be in the Enterprise edition you can view it here.
Q: Please, we need documentation and a lot of it?
A: For Odoo 8 there is slowly coming better and more documentation which you can find here: http://odoo.com/documentation and they've started writing the documentation for Odoo 9. Fabien announced that he wants to have atleast 50% of the documentation for V9 before Odoo 9 is released. (see https://www.odoo.com/nl_NL/groups/community-59/community-13246232). So I think documentation will only get better from here on.
I hope this answers all your questions!
Yenthe