I think the cast did a good job if it was their first time starring in this series. Of course they can't compare to other stars that have a lot of experience, but they did a good job for their debut starring role.
NO, a lot of the cast from this series is in Twilight of a Nation. Did you even watch Twilight of a Nation? I forgot to mention that they are mostly in supporting roles, but most of them are all in here. Besides the ones that you mentioned, Jimmy Au, Wong Man Ming, the 2 that played Jimmy's sworn brothers(Liang Hong Hua and Jun Xiong), Rong Hui Wen, Lai Han Zhi, Carrie Choi, Leung Kit Hua, Chan Wing Chun and I think a couple of others too but I don't remember every single one... However, quite a lot of them are from this series.