This is well writtenI will try to answer all your questions but if I miss anything please let me know.
1. Because your earrings are vertical, on your ears as to on your hand, the light does hit earrings differently than directly from above for rings. Thus you won't usually see the same level of sparkle all other things being equal. And you (from your viewing direction of your ears) do not see earrings the same as you would see a pendant on your neck. Things like your hair obscuring light from hitting the earrings will affect how sparkly they look compared to your ring or your pendant where light does not have as much obstruction.
2. Diamond studs - This is very very individual.
Color tolerance. This depends on personal preference and skin tone of wearer. Some people are not super color sensitive, and either don't notice color in diamonds, notice and don't care, or don't care at all. There is no judgement here. Everyone is different and has different preferences. If you have warmer/darker skin tone, a lower colored diamond may pop a lot more than if you are very fair. That can affect how a diamond appears on you. I have a pale olive tone, and personally I am very color sensitive, and prefer very white. My studs are D color, but I have a very dear friend who loves her J colored studs, and they look absolutely amazing on her. There are people that prefer some warmth in their diamonds and that is perfect for them too. I do not subscribe to the "higher color is best". It completely depends on the person. I have a J colored old cut diamond pendant that I love and would NEVER trade.
Cut. Cut makes all the difference in how sparkly a diamond looks. It does not matter if you have a D colored stone. If the cut is poor, it will just look white and dead, no sparkle at all. So "excellent cut" is a good start. However, "excellent cut" even by GIA standards is a very large range. If you are considering studs, and are looking at GIA grading reports, make sure you stay within these parameters to be safe: table 54-58, depth 60-62.3, crown angle 34.0-35.0, pavilion angle 40.6-40.9. This will get you more rainbow fire. However, if you like more white light return, go for diamonds that are have around table of 60 and depth of 60. Most importantly, when you are actually shopping for a diamond, trust your eyes. And don't get tricked by the professional lighting at jewelry stores. When I am shopping, I actually take the diamond to a dark corner with very little light, or I will actually take it under the counter without light, and if the diamond seems kinda dead, that means it's not well cut. Well cut diamonds, in dark light will still have some sparkle.
Clarity. If you are concerned about inclusions, I would stay at VS2 or above. Inclusions I would avoid are clouds and black spots. Clear spots are not too much of a concern. If you are open to SI1, I would choose ones without a feather at the edge, as well as avoiding clouds, internal graining, and black spots. How much you care about inclusions also depends on you. You also mentioned that you do not want to see inclusions close up. Usually, if I cannot see them with my naked eye, I am fine with it. However, if you use a loupe, your chances of seeing the inclusions are much higher. For an SI1, you may or may not be able to see with the naked eye. It depends on the type of inclusion, and your own eyesight. You would have to evaluate in person. For me, I am ok with a very clean SI1 for earrings as long as the cut is super ideal (stones that have tighter cut parameters than just "excellent" by GIA) and the inclusions do not affect the performance. For rings, I usually require at least a VS1, not because I can see the inclusions with my naked eye (I cannot) but because I like just knowing my diamond has few inclusions. It's mental and it's my issue.
Fluorescence. Medium to strong fluorescence can (but not necessarily does) result in haziness in higher colored diamonds, D-F. You would need to evaluate in person to know. And you may need to compare it side by side with a D-F without any Fluor. In a I-K stone, fluor could make it look even whiter. This is all very personal again. Some people look for stones with fluor because they can be a great deal b/c stones with fluor are usually priced lower due to the general "fear" that they are "not good". A trust worthy vendor will tell you if there is any haziness, so I would not turn down a stone just because there is fluor. However, if you are concerned with resale value (not that there is much with diamonds) be aware that a diamond with fluor may be harder to move.
So to answer your question, I prioritize CUT first, then COLOR and then CLARITY, and then SIZE last. Please note this is all with regard to modern round brilliant diamonds. If we are talking about Old European Cuts, then this could be different.
To bring this back to VCA, their diamonds from my naked eye evaluation, are very white so I believe the D-F claim, and that they are very well cut. I will find the picture of the ideal scope pic my friend took, which shows the symmetry of their pave stones. This pic to me also makes sense given that diamonds from my pave pieces are very sparkly to me. So the reason that the sweet pave earrings may not seem that sparkly to you is because they are just very small diamonds and your personal viewing angle. When you go shopping, you should have a friend wear them and you evaluate them on her ears, and see if you like what you see because that is what other people are seeing on you.



I am glad you mentioned the parameters!
That part I do not have memorized.
I am going to practice picking out loose diamonds on the internet by using the parameters you suggested!