E21 Fuel line fitting help

I am replacing the fuel lines on my 82 320i and I'm having a problem with the hose that runs from the fuel filter up to the top of the passenger side tank (accessible under the rear seat).

First Problem: Does anyone sell a replacement hose like this with these fittings on each end?

Second problem: How do you disconnect the hose up top? It has a nut and a fitting that runs to a hard line but it doesn't seem to make progress when I turn the nut, it just slowly spins around. Im not sure if I'm damaging it or just not being patient enough. (see the attached picture)

Anyone done this before?

**update**

I was able to order the hose in question through my local BMW parts department.
Should arrive in a week or less.

But I still have no clue how to disconnect it! I guess I have a week to figure it out.

Have you considered asking your local BMW service/parts manager for advice? Some are happy to help, others not so much. It's worth a shot. I did that several times successfully when working on my Subaru.
Good luck!

That type of fuel connector uses "banjo" bolts, they are hollow and have holes drilled in them so fluid can pass through them. Since you are having trouble re-threading the bolt I would first make sure that there isn't the end of a bolt snapped off in the hole, these bolts are prone to breaking, I'd replace the bolts if possible and be sure not to over torque them, if the holes directly under the bolt head are eclipsed at all replace it, they should be perfectly round. If there is a bolt broken off get an appropriate size easy out to remove it, if the threads are shot use a tap (these use pipe thread pitch if I recall correctly) and run the threads. Be sure to clear the hole of any metal shavings afterwords because your engine won't like ingesting them.
Hope this helps.