No, a wizard can only copy spells of levels they can actually prepare.
Unfortunately, as the rules describing the wizard's spellcasting and spellbook state:
Copying a Spell into the Book. When you find a wizard spell of 1st level or higher, you can add it to your spellbook if it is of a spell level you can prepare and if you can spare the time to ...
Disciple of Life:
...Whenever you use a spell of 1st level or higher to restore hit points to a creature...
In this particular instance you are using a class feature to restore hit points. Despite being a derivative from a spell's level the spell itself is not what is healing you. When you "use" spirit guardians, it is to deal damage. The spell ...
Hypnotic Gaze is not a spell
The rules for targeting spells do not apply to things that aren’t spells, so you don’t need a clear path.
Nothing can pass through the barrier
Hypnotic Gaze is not nothing even if it’s not a spell so it can’t pass through the sphere.
As an aside, “shimmering force” may or may not be transparent.
No, Disciple of Life only works with spells
Disciple of Life states:
Whenever you use a spell of 1st level or higher to restore hit points to a creature, the creature regains additional hit points equal to 2 + the spell's level.
Grim Harvest is not a spell, so it cannot trigger Disciple of Life.
You remember your prepared spells indefinitely unless an effect indicates otherwise.
Generally when preparing spells, you keep almost a full casting of the spell memorized, which is then later triggered by verbal or somatic components.
There are no rules that explicitly state under and circumstances that you would lose access to prepared spells in the ...
Disciple of Life only works when a spell heals as part of its description, not when something outside the spell does the healing.
The Disciple of Life feature states:
[...] Whenever you use a spell of 1st level or higher to restore hit points to a creature, the creature regains additional hit points equal to 2 + the spell’s level.
The Grim Harvest ...
You can't see through the sphere.
Nothing--not physical objects, energy, or other spell effects--can pass through the barrier, in or out...
This includes light, so the creature can't see its surroundings.
There are some important differences between your specific scenario and this one, but Curse of Strahd does contain a bit of plot with some rule guidance on this.
The NPC Patrina Velikovna can be restored to life via an effect that is described as identical to the resurrection spell except that it works regardless of how long the creature has been dead. If ...
RAI: Unless the attack hits automatically, yes
There are two people who can know whether the attack hits; the player or their character. In both cases the answer is the same.
In every game that I've played, players are not supposed to have knowledge of a creature's statistics, including to-hit modifiers. Additionally, they do not know all the ...