Drupal 8 will answer most of those out of the box, apart from support across MySQL and Micrsofoft SQL (a lot to ask!). Drupal 7 less so. On the question of Drupal and MVC see http://www.garfieldtech.com/blog/mvc-vs-pac which largely holds good for Drupal 7, though not Drupal 8.
In D7 the basic architecture is that a single request gives a single page response, with web services integration is with contributed add-on module(s). D8 will move to being able to serve pages, elements of a page, any chunks of data in non-html formats, in response to requests.
Not sure what you mean by jQuery as base for backend. If by backend you mean the kind of backend / frontend distinction in Typo 3 this does not map to Drupal architecture. In D7 jQuery and various libraries are included, with version is 1.4, upgradable by contributed module, 1.4 being the version current when D7 was released: D8 policy will be to allow Drupal core to change versions of jQuery with minor version upgrades.
Note D8 will look quite similar to D7 but is totally rewritten with strong integration of Symfony framework for handling http requests and routing, and with a strong move away from Drupal's legacy of procedural code. A D7 to D8 upgrade will probably be very difficult.
Commercial pros and cons: for good developers who are not yet Drupalistas, Drupal is notoriously easy to get wrong and under-estimate, both losing money for the developer and delivering a poor and troublesome product to the client at the same time. On the plus side, once you have earned Drupal skills (probably the hard way) there is a great deal of work and opportunity.