Primary Cat Removal: Defeated by a shield bolt.. lol!

[microfiz]

So I own a 2001 LE (3.5 L). Last week, I heard a loud rattle emanating from the driver's side. I took a quick peek and found the second half of the primary cat was loose). Ordered a Cal-approved cat from Rock Auto and proceeded to remove everything yesterday. It looked like I needed to remove the heat shields (two) for the cat to gain access to the exhaust bolts (6). There were also 6 heat shield bolts that I needed to remove, and I got 5 out except for 1 (at the bottom, and presumably more affected by moisture). I think I may have even stripped the head off after spending 3 hours on it.

 

Anyway, this is a multi-tiered question:

1) since the car is not throwing codes, the single row of ceramic seems to be doing an adequate job scrubbing the exhaust. Should I just forget about replacing since the car is running good?

2) is there another way I can gain more access to that bottom exhaust bolt so I can use other tools OR even grind it out? Can putting a jack on the engine help?

3) how about removing the manifold outright (driver's side)? Is that hard?

 

Thanks any advice in advance. =)