MASSPLUMBER- just what I needed to know, thanks!
As a novice, doing this in sub-freezing weather is challenging.
I shall follow your advice whenever it "warms" up a bit.

When I was a little fella, maybe 10, Dad taught me the only way he knew how. Clean, flux, tin and wipe with damp rag. Heat assembly and add solder and wipe off excess.

I don't do all those steps anymore except when having to deal with an old fitting. As the fittings get larger, the harder they are to do and it sometimes takes a bigger hammer (BFH). I mean torch.

KISS, thanks for graciously letting me butt in on your threat:o
It was hard to pass up getting in with a couple of pros, and a cold-weather one to boot!

Pdw: Your welcome. Very related.

I found another option.
There is a Sharkbite angle stop. Seems like I can unsweat the stop and use a Sharkbite stop.
Comments. It's made by Brasscraft, but I forgot to write down the model #.

The large extension stop I found, but it's not 1/4 turn.

I guess some of you were wondering how it turned out:

Main supply valves where there weren't any before. Before and after pics.

Ball valves for the vanity and toilet. 1/2 NPT female adapters for the possible addition of a recirculator. Labeled. Wires tidied up. Pipes supported with ceiling flanges. Forgot and may do later: fire caulk for penetrations

The old and new angle stops.

The old: sweat with 5" integral extension multi-turn. Note the unexpected pinch I had to deal with.
The new: 3/8 female adapter, 3/8 NPT chromed copper with 3/8 IPS 1/4 tuen angle stop.

The female adapter can be concealed under the bell flange. I had a little trouble with the bell flange staying on because of the threads because it sits on the threads, I used a piece of foil tape on the threads.

This would have been another good choice: Watts: Angle - Quick-Connect | Brass & Tubular

It would keep things very close to the wall and look nice.

Use of heat shield and a piece of metal to protect ceramic tile. I could use a full-size propane torch.

The bell on the cold water side was cut off with my new toy: The Multimaster and it did a nice job. 2nd choice would have been the Dremel tool with an abrasive cutting blade.

Final repair with penetrations caulked on this side and new shelf paper.

I got side tracked a bit and sanded the rusty bell flange on the toilet and gave it a rust treatment with Extend. It's ready to paint black.

I also did the same with the toilet pipe.

O know, I should replace the supply hoses with braided ones.

About $10 for the stops and less than $2.00 for the chrome pipe. The bell and the female adapters were cheap too and so were the few copper fittings. The ball valves were about $8.00 each. I could even get the non-quarter turn angle stops with the extension and bell flange easily.

I don't like compression. Swage is OK. Compression, Yuk.

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Hello Keepitsimplestupid - I have done a few of these types & they are sodered. & the crom makes the difference in the ( O>D> )of the other copper pipe. I would remove the old ones and replace with new compression cut offs. Hope this helps If it does rate me below. Good Luck & GODBLESS::::: F.B.E. ( OH by the way did you tell them when they told you $100.00 ,You should have said 9 I don't want to buy the factory, JUST A COUPLE CUTOFFS ) HaHa HA ;:: F.B.E.

It looks like you installed two adapters and I can't really tell from the photo but it looks like one is on the hot and one is on the cold. May I ask why? Are you going to recirculate your cold?

Yep, I did. Here is the one I like so far that doesn't require a return line. Hot Water Circulator Recirculator Circulation Pumps I just don't want to put it under the sink if, and when, I decide to install one.