HKS a internal PHP framework only joomla

-- HikaShop version -- : 2.4.0
-- Joomla version -- : 2.5.8
-- PHP version -- : 5.5.8
-- Browser(s) name and version -- : many

Hi
I already ask those kind of question in the forum but need to know more about PHP CMS framework and availability of library over PHP CMS framework .
I am more an javascript and CSS HTML guy but since javascript go to MVC , i hope joomla model will stay to MVC ( rather go to the wordpress model) and ll be not use general library ( framework) in the feature . IF All CMS use the same standart php library ...why choose CMS1 rather than CMS2 !. It rather difficult to see the limit beetween a framework and a library since a library is a component of many library that avoid us to use third library . I read that some framework ll Go to CMS ( htpp html gui for easy setup options/parameters ) direction and some wellknow CMS ll got to the framework direction ( easy to use efficient high level third library ) . I read in the past bad things about feature in hikashop forum developpers !!

Here my questions
1 Could we understand Hikashop implement some "PHP framework " functionnalities on joomla PHP framework ?

2Does all php library ( Framework) could be add easely to joomla like javascript library ( Framework) ?

3 How many php Framework that work on joomla php framework exist ? I read nooku but the documentation say easy to install and test but use vagrant !!! ( easy for php developper ? not php beginner !)

4 Does hikashop override / wrap / update some side of the joomla php framework ? If yes in which side . I think user is one of them but don't know others ....Does it mean we could use hikashop API in this specific case instead joomla php API framework ?

5 Does make acessible a php Framework in joomla is manage by a joomla file ?

6 is there now 5 april 2015 some hikashop library to output hikashop data ( product or not ) in a json structure to be manage by a javascript MVC client side interface ?

7 joomla add in the server side specific tag like angular do in the past with directive for client side . Joomla specific tag break the php compatibilities that php/html IDE understand for merge data (<?php include ) . Is there some php IDE that are php joomla compatible ? in a way many php file wrap/contain html tag/directive so ...jdoc is a new tag directive only use by joomla parser/processor !
which file name process the index.php file that contain jdoc directive ?

8 is there some CSS framework ( gantry ? T3? ) that come with their own php library or joomla php library ? Howto discover this by have a look to the source code ?

Regard's