do you know if is ti possible change variant option once you have the assembly loaded in NX managed?
For the different variant configurations you need to reload the assembly using the new variant. I am not certain about the exact version but I think prior to the NX 8.5 there were variant configuration options available in the assemblies menu.
One more question....is It possible open and load the variant from NX and not to have to choose the option from Structure manager and then from TC an NX?
Variant rules,configurations are created in Teamcenter. So you can apply a predefined variant rule to an assembly in the assembly load options to load different assembly configurations.