what is better… to recite different surahs in wajib namaz after alhamd or the mustahab given in tawzee ie. 1st rakat qadr n 2nd rakat tauheed….in order to improve concentration n obtain benefit of other surahs I wanted to recite them in my wajib daily prayers….can I recite them as the 3rd surah?

You can not recite more than two Surah.if one has Tajveed issue then follow the ruling of tsuzeehul Masayel that in first Rakat read sura Qadr and in second rakat surah tauheed after the recitation of surah Hamd. But if tajveed is perfect then get the sawab of the recitation of different surah.