HasMany is currently working very limited in ExtJS currently, so Bancha can also only support basic operations.
Bancha and CakePHP will provide you with a lot of out of the box solutions. CakePHP is a PHP-Framework (like Symfony) which makes it very easy to do all kinds of standard functions, like validating data, saving data, etc.
Checkout some of the CakePHP tutorials to get an idea of what it is doing. If you are new to PHP, I can tell you in the long run you definitely want to use a Framework. Most famous are Symfony, Zend Framework, and then CakePHP ;-)
In the next two or three days there will be a major release, but I can't say too much yet...