Yes you can use sorcery points while raging
Rage prevents casting spells while raging:
If you are able to cast spells, you can’t cast them or concentrate on them while raging.
However, using sorcery points is not casting a spell and thus is not forbidden by rage. A spell would say that it is a spell and/or that you are casting it. Hound of Ill Omen says no such thing.
Very similar to smiting while raging
This is basically the same case as a paladin using divine smite while raging.
when you hit a creature with a melee weapon attack, you can expend one spell slot to deal radiant damage
This is a case that Jeremy Crawford has ruled to be within the rules
Divine smite is not a spell, yet it is fueled by spell slots. Because it is not a spell, it is not affected by things like Rage that prevent spellcasting.
If spell slots can be used, there is no reason why sorcery points couldn't.
The duplicates aren't creatures
Per the mirror image spell description:
Three illusory duplicates of yourself appear in your space. Until the spell ends, the duplicates move with you and mimic your actions, shifting position so it's impossible to track which image is real.
Nothing in the spell description says the duplicates are creatures - they're just illusory copies of you.
...But attacks can always be redirected to them regardless
The description continues (emphasis mine):
Each time a creature targets you with an attack during the spell's duration, roll a d20 to determine whether the attack instead targets one of your duplicates.
If you have three duplicates, you must roll a 6 or higher to change the attack's target to a duplicate. With two duplicates, you must roll an 8 or higher. With one duplicate, you must roll an 11 or higher.
Anytime you're targeted by an attack while mirror image is active on you, the spell can redirect the attack to one of your duplicates. The spell makes no exceptions regarding whether the attack can only target creatures.
As the intro to the PHB/basic rules states:
Specific Beats General
This book contains rules, especially in parts 2 and 3, that govern how the game plays. That said, many racial traits, class features, spells, magic items, monster abilities, and other game elements break the general rules in some way, creating an exception to how the rest of the game works. Remember this: If a specific rule contradicts a general rule, the specific rule wins.
It's because "specific beats general" that any attack that targets you, even if it normally can only target a creature, can be redirected to a duplicate as well.
The duplicates can't be intentionally targeted, either
The illusory duplicates can't be intentionally targeted separately from you. As the first quoted pair of sentences state, it's impossible to track which image is real because they move with you and mimic your actions. Thus, anything that would attempt to target your duplicate would necessarily have to be trying to target you - which of the "duplicates" actually turns out to be you is determined randomly by rolling a d20.
Anything that's not an attack doesn't interact with the duplicates
A later part of the spell description says (emphasis mine):
A duplicate's AC equals 10 + your Dexterity modifier. If an attack hits a duplicate, the duplicate is destroyed. A duplicate can be destroyed only by an attack that hits it. It ignores all other damage and effects. The spell ends when all three duplicates are destroyed.
As the spell itself states, the illusory duplicates have no mechanical interaction with things that aren't attacks - whether it's a spell requiring a saving throw, a non-attack monster ability, a class feature, or something else. Unless it's an attack, it doesn't interact with the spell at all.
(Note: grapples/shoves are "special melee attacks", so they can be redirected to the duplicates - but since they don't have attack rolls, they can't "hit" the duplicate and simply fail if redirected to a duplicate.)
Best Answer
I would say no to the spell you are quoting (which states "summon a hound of ill omen to target one creature you can see.) as this seems to go against the PHB section on "targets" for spells. Nearly all spell types or effects it must target something (odd exceptions such as teleport and sending etc) and the PHB section on spell targeting says: (emphasis mine).
since it is highly likely that scrying wouldn't have a clear path to the target (possible if you are on a flat plane with EXTREME line of site but generally speaking)
The scrying spell only notes that you can see and hear as if you were there, it does not say you have a clear path to the target (speaking as a rules-as-written) or can act as if you were there.
Other spells depend. I would say no to long range "sight" spells such as meteor swarm as they would break the need for a clear path to the sighted target. Sending would be irrelevant as you need the same criteria for scrying anyway. Teleport would also be iffy - simply seeing somewhere does not make the location "known to you" as such. I suppose that is a DM call on what they consider "known to you" (I wouldn't consider a "common" room as "known to you", but if there were identifying parts that made it "known to you" such as a window looking onto a recognised item or location then OK you draw where you want to go and teleport into that stone wall).
An episode of the WotC podcast also clears targeting up: You always need a clear path to target a creature with a spell. You don't necessarily need to be able to see them (i.e. heavy fog wont impede) but the travel path of the spell must be clear. The spell originates from the caster so the travel path from the caster to the target must have a clear travel path. Full cover stops travel path (including glass).