... for the searchers who may find this thread ...
When the lines are ugly at the sending unit, many times they are still okay down at the front of the tank. They join the hard line just aft of the mustache brace under the car. It's a much more accesible location, and many times it's the only way to get things apart without twisting up the hard line that comes off the sending unit.
Soak the ever lovin dogshit out of them with the penetrant of your choice, and use flare/tubing wrenches. Many times, it helps to put them in a clocking that allows you to rest one against the body while still giving you room to squeeze them together. Just put pressure on them, and then give them a little "snap" with your other hand.
Wear gloves to protect your hands and eye protection to gaurd against any fuel spraying out if the system is still under pressure!
Now, you can cap the lines to keep crap from getting in there, and pull the sender with the short hoses still attached, letting you swap out the pump, and do what you have to do without hassling with the rusted fuel line fitting on top of the tank
It's important to note that if you go all McGilla the Gorilla
on the connections at the top of the tank and the hard line on the sending unit get twisted up/distorted, you may end creating a restriction in that section of tubing that will kill the fuel volume that the pump can provide.
... and that can kill your motor at high rpm's when things lean out from lack of fuel ...
Just take your time, and even the worst corrosion can be dealt with.
I've seen a few vr-4's that were so corroded on the top that the studs were just stubs and the nuts were just an unrecognizable blob.
I removed the lines at the mustache brace, dropped the tank, and split the nuts off with a dremel tool by cutting them top to bottom with a cut-off tool. Then you just pry the nut open with a screwdriver, leaving the studs in suprisingly good condition, and ready to take a new nut.
As far as removing the battery terminal with the engine running ...
Flying Eagle and SouthCaliVr4 are spot on in their advice.
Removing the battery terminal with the engine running may have worked on your uncles 73 plymouth duster, but on these cars, there are many things that may be damaged by this "trick". From the ecu to the etacs module, abs computer (and on and on,) you may be making a simpe problem into an electrical nightmare
Not to mention you will probably pop the diodes in the alty when you reconnect it if it does stay running ... killing a perfectly
operating alty ...not recommended
, to say the least!
Take your time and troubleshoot this problem logically.
A fuel pressure gauge will tell the tale if you're having a problem with pressure/volume/delivery.