Hi rekha
As you said we have inbound and outbound interafces.
Interfaces can be normal file interfaces,idocs,pu12 interfaces.
To update single or multiple infotypes dont use bdc because infotypes screens may change in future
We have hr_infotype_operation , hr_maintain_masterdata fms to upadate PA INFOTYPES and search in se24 with cl_hrpa* you will find separate class to update each infotype
To update OM infotypes fm is rh_pnnnn_maintain
Thanks
Kamesh