Hi Ankesh,
1) In the view you can read the context node value as -
lr_entity = me->typed_context->context_node_name->collection_wrapper->get_current.
lr_entity->get_properties( ls_attr).
in ls_attr you can get the BP Partner value.
2) You should not write select query. You can use the bol search and other bol relations of BP.
3) If your purpose is only to display this new field in the UI level, you can add a value attribute to the existing node itself.
4) For value attribute, you don't need to enhance anything in BOL. You can write the Logic to fill the value attribute in the BSP component itself.
Please let me know if you have any doubts.
Regards,
Rachna