Broken Shut Off Valve Kitchen Sink - DIY Replacement?

[FredSanford]

I broke the handle off my hot water shut off valve under the kitchen sink. I believe the shut off valve is connected via compression on pipe at the wall as well as the copper pipe running vertical to the sink hose. My thought is to replace the shut off valve and change out the copper pipe for a flexible connecter.

A few questions I have are:
1) If above is accurate (i.e compression currently in place), can I use the same nut and ferrule ring currently on valve (at wall)?
2) It appears there is a "coupling" of some kind on the copper pipe that attaches to the black faucet hose. Should I keep that or remove that and just screw into the faucet hose?
3) I picked up a flexible connector that states it is for compression on both ends ("compression to valve" and "compression to faucet"), if I am attaching to the black hose via threads to threads (i.e. just screwing it together) does it matter that the new flexible hose has compression parts "built in" or will that cause an issue?
4) Finally I assume the white around the valve and ring on wall is plumbers paste? Any concerns with that causing problems with the removal/loosening and replacement of the nut? Do I need to use anything like that during replacement?

Because I will need to have water off to the whole house, I want to make sure I plan for everything before starting! If I am thinking about this wrong, please let me know. Thanks in advance.

 

[FredSanford]

Bumping for visibility

 

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[GReynolds929]

1) yes, you can but it is recommended to replace all if possible.
2) if the faucet supply is long enough to reach then connect it directly to the shut off.
3) the flex connector would need male threads on one end, but is not needed if the faucet supply is long enough to reach the valve.
4) no concerns for removal. I always put a little on the new threads to help the threads mesh together easier.

 

[FredSanford]

@GReynolds929 Thanks for the reply

 

[FredSanford]

I switched out the shut off valve and was able to use the faucet supply line. One question that came up as I was connecting the hose...any idea why the previous installer used the copper pipe to the faucet supply line vs going direct as well? Is there any concerns with the connection directly to the shut off valve I need to be aware of? I had picked up the flexible compression line but went this route and happy to return those if no concerns.

I did have a few drips during testing - mainly happened when I turned off the faucet (vs. while running). I tightened up the compression nut a little more and seems to have stopped - I dont think I have much more play to turn the nut. Will wait for any residual water to dry that may be on the pipe and try again. Thanks

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Thanks.