Shradh is a ceremony where we remember our departed parents and grand parents (called pittr or poorvaj). we invite a Pandit and he does some pooja and sankalp and then we serve him the same variety of food liked by our dear ones and give him Dakshina.It is considered that the day our poorvaj died like on dooj, teej like that, in that tithi they visit us, and feel happy and satisfied when they see our love for them,and bless us.
Earlier traditionally nobody bought anything new or did any auspicious work in those days,but i think why not? they are our loved ones and they wud like us to be happy so.....
This day is a symbol of our Indian culture where we give respect and love to our departed souls also.and remember them with love.Its only our emotions which make it more meaningful.