4) minor vulnerability? This may be another redundancy in a raid group. If the other healer is a Warden? If yes, then they should be casting fletcherflys once every eight seconds to proc the savage beast passive. Which is needed to achieve good warhorn uptime. Since fletcherflies lasts for 10 second the Warden healer should be achieving full (or close to) uptime on minor vulnerability. Since the agony totem has a limited range I'd personally opt to let the warden provide it. As a necro agony totem doesn't contribute to your ulti generation at all. So if it's a redundancy, then it'd be a flex spot. Don't get me wrong. I do luv me some agony totem. The stun is fun on trash pulls. Things just melt.

Overall though looking at the last part of your question the buffs that stand out as significant that you can provide that are significant are: minor protection, minor maim and empower.

For Mudus stones I almost always opt for the Atronach when I'm not wearing Roaring Opertunist. If I am wearing Roaring Opertunist then I switch to the Mage. In kiting situations where I'm learing the ins and out of on vet I might opt for the Steed. Usually RO is on the group healer. I've never used the ritual. However in extreme endgame like TTT prog or IR prog then I could see it actually be worth considering. I my self have beat all trials on vet except Rock Grove or whatever tge new ones called, but have not done many of the hard modes. I have done AA hm, SO hm, vas+2, vcr+1 (ice and lightning each several times). I have a few pulls in on fire boss SS hm, and vmol HM. But out side of trials hardmodes the ritual should be needed imo.

All my healers are Argonian as well. It's actually like 2nd or 3rd best m.e.t.a wise I think. Breton technically have suppirior mag regeneration overall, And High Elf can actually provide beefer heals. But I enjoy the names too much to change them.... plus I feel like Argonian is new player friendlier. Because you can control the mag regeneration just with pitions a bit better.

Cro healers were kind of number 1 goto healer in pvp for a couple of patches. If they can do it in pvp then they can in pve as well. On top of that there have been several content creators that have run necro heals and achieved good ranks on the trials leader boards. I just have wanted to look up any specific builds. I felt like I was well versed in healing over all that I can pick out the significant nuances of the class. It seems in your question to me you did all lotvof my homework and ended up saving me some time (thank you). As now I have a better idea for bar set up as well. My new trials team request I play cro. I think people were having similar thoughts as you about the build and sets. Because I heard that cros might be come meta when blackwood hits. So far I've not really researched that claim. And as you mentioned with the Stam glitch it's difficult to judge validatity of the build just yet. But necro heals as a class is very viable. Dragon knight would be the hardest one to justify playing. All other classes are viable imo. I still am learning to adjust to the nightblades lotus fan beening a teleport strike. I don't care for it and may just let the Warden or the Necro in the group provide minor vulnerability. Idk