Engine help --how to install a new front pipe on a 98 corolla

help --how to install a new front pipe on a 98 corolla

I need to install a new front header pipe on a 98 corolla. I know it can be done. I just want to know what are all the extra parts I should get with it? Are there any torque values I need to be aware of when tightening the bolts? Also I noticed that there are springs over the bolts at the front of the front pipe do I have to compress them to get them off? Also do I have to weld the front pipe and the cat together or are they help on by a clamp? Please respond thanks.