Metal Brake Lines/Exhaust Question

Im replacing the metal brake lines on my 85 Olds 88 Royal.

I'm assuming I'm going to have to buy the metal tubing from somewhere other than an autoZone/advanceAutoParts because they only sell lengths up to 60" (5ft) and i need a length longer. I have the flaring tool already, is there anything else im going to need, and where might I find the proper tubing. I need a length of about 15ft.

Also, I have a pesky 14mm nut that WILL NOT BUDGE and the corners seem a bit rounded. It is on the old break line that needs to come out. Somene suggested a tool specifically for stripped nuts, any ideas?

Im installing a new exaust system from the catalytic coverter to the tailpipe, It doesnt seem to be hanging right though. If anyone can show me pictures maybe I can see what I did wrong.

Any help and any links to documentation would be great. All I have right now is the DIY manual from autozone.

60 inches is the longest line, you have to make up double flared unions, you will need the tools to do this. On the rounded nut, break the line off the rounded fitting, then you will need a socket that is made especially to grab the rounded flare nut, or use PB blaster rust penetrant and vise grips.

You can buy bulk line and cut it to size.
Comes in 25 ft lengths..a good autoparts store should carry it.