I was able to get the tube out of the plenum by removing the studs that mount the lower end of the tube flange, and cleaned it out. It was totally plugged with carbon at the top but the bottom end was clear. After some finagling I got it reinstalled. It's a bit hard to maneuver into position even with the studs out, but it's doable, have patience.
One caveat: While moving the pipe downward, I did feel it sort of give a little bit at one point. For a moment I wondered if I cracked it or something somewhere I couldn't see, but I don't think so. It was silent, and It felt more like maybe the other end might have loosened or turned a bit where it screws into whatever it screws into or perhaps it kinked a little up under the plenum where I can't see. That's what I'm guessing it was. But, it was only a small movement so I'm not too worried about it. I just wanted to mention that because it is a possible concern. Whatever that was, the pipe didn't seem to get loose nor did it become noticeably easier to move or bend that it was at first. That's mainly what makes me think I might have just felt it kink a little bit somewhere further up. I should probably try to get my hand up behind there while it's running and make sure I don't feel or hear or smell any exhaust leak. I'll try to get to that tomorrow and report back. I certainly don't hear or smell any obvious leaks.
I was able to get the EGR exhaust pipe reconnected with much less effort than expected. I got it bent back close to where it needed to be and then removed the EGR mounting studs, (same size E7 Torx socket) and screwed the pipe flare nut onto the EGR by hand to be sure it was aligned properly, snugged it up with the Crescent Wrench, and then put the EGR where it needed to be (with the gasket behind it held there by pushing the EGR against the manifold) and started the studs by hand, then the wrench, and replaced the nuts. Then I cranked the big flare nut down tight with the crescent.
To bend the pipe back, I used a 1-inch tie-down strap looped around the pipe and a 2 x 4 stretched across the engine compartment from near the windshield to the body member just in front of the radiator. Then I used the ratcheting buckle to crank the pipe up to where it needed to be. This worked extremely well; it's gentle on the pipe, no dents or kinks, and you can put it right where you need it to be. You can then check the position by putting the EGR valve back in and see where the pipe end is in relation to the nipple. It really works great for this. Then get it very close; it probably wont allow threading the nut on at this point and you shouldn't try to force it in any way. You should be able to screw the nut all the way on or nearly so, by hand or it may not seal properly. This is why I decided to, at this point, remove the EGR mounting studs, allowing complete freedom of movement for aligning the EGR, and tightening the big nut, and then using the EGR itself to pull the last little bit of pipe offset into alignment by just mounting it. Note you probably should have the fit _very_ close to where it needs to be before cranking everything down, as I did. The tie-down strap trick really made this quite easy.
I couldn't get to the EGR temp sensor plug so I unscrewed the sensor while still connected, twisting the wires, hoping I didn't break one inside the insulation. When replacing it, I put it in before mounting the EGR so I was able to screw it in by turning the whole valve body rather than turning the sensor. I should have done the same thing to remove it, ie left it in till I took the EGR off then turned the valve body to unscrew it. C'est la vie.
Bottom line: All done, everything works, no CELs, Gas mileage is back to where it should be, and runs perfectly! I hope this helps anyone who needs to do this job. My Maxima is a 3.0 L 2000 and 1/2 SE. (some parts changed in mid-2000) I don't know exactly when they switched from the older tube that had two mounting bolts at each end, to the one like I have that sticks up into the plenum.
If you decide to try this, be careful and slow moving that pipe, keep the pry bar back away from the nut so you don't deform the pipe anywhere near the nut area, (I don't think I deformed my pipe at all doing this) and don't bend it any more than is absolutely necessary. Have your socket in your right hand and the pry bar in your left and slide the socket onto the nut as soon as you can, as you carefully, slowly push the pipe down. It's actually quite easy to bend, so be prepared for that, and don't get aggressive about it. Gently does it. This way you assure the deflection is at a minimum, and you'll see the pipe will even spring back quite a bit when you remove your socket. Be patient, use your noodle, and this is definitely a doable job.