HI Naddy,
Regarding the point no.1 yeah you can enhance the structure so that the fields included in the HCMT_BSP_PA_XX_R0105 will be available to be added in the component configuration.Ensure that the field added in the above structure is also there in PA0105 table and the same is been maintained against the employee.
So in this case after doing the above mentioned setting then implement the BADI - HRPAD00INFTYUI
Maintain the methods IF_EX_HRPAD00INFTYUI~INPUT_CONVERSION , IF_EX_HRPAD00INFTYUI~OUTPUT_CONVERSION.
Regarding the point no.2 i don't suggest this if you want anything to be displayed as a part of a infotype then if that field is not available in that infotype then better enhance the infotype and follow the procedure as i mentioned for point no.1.
Regards,
Mithun K