exhaust help, what parts i need etc.. Options

[Mike95ST]

i need my car to pass inspection and my only problem is emmisions, theres a hole on the bottom of the flange between the cat and the downpipe, both ends of the cat are rusted and so are the bolts on it, since my mom hasnt gotten me a graduation present yet, she said she'll fix my car, so i figure i may as well buy a whole new exhaust from the headers back, i found a blueprint with oem part numbers and www.toyautoparts.com has every piece i need. What i need to kno is should i replace the Oxygen sensors too? anything else i should considering im gona do this myself. What types of nuts n bolts? My step dad said if i break the bolts when i unhook the downpipe from the headers ill have to have those rethreaded, etc.. anything im no thinkin about..i dont see replacing the exhaust being very difficult

[Mike95ST]

and jus curious my car has a o2 sensor in the manifold, would it make much of a difference if i got the headers without the o2 sensor?

[Mike95ST]

help please?