Like I said, you definitely want Body 3. The question is: do you want to massively overpay to have it right away, rather than in 15 karma?
You can refluff mentor spirits however you want, but there's no rules for designing your own advantages/drawbacks. Cat and Spider are you best choices right now (you can easily make that Composure (3) test), Horned Man is fine if you go Intuition rather than Charisma (better bonuses, but a meaningful drawback). Trickster and Seductress are alright.
Binding is something you want to be as good as possible at, but there's not a minimum threshold of "must have at least this much." Binding 1 is useful. Binding 4 is better. Basically, the more Binding you have, the more cost-efficient it is to use. It is good because spirits are good, and you can have bound spirits help you in a lot of ways that summoned spirits can't, like Aid Sorcery. Even crappy low-force spirits have uses, like having a Spirit of Man know a buff spell and cast it on everyone, then hang out chilling with its huge Sustaining penalty on its home metaplane. Invoking (metamagic) is super ultra win times as well. However, it takes time and money to use Binding. I would either start with 4, or start with 0 and buy it with karma. 6 points will get you rank 1 and a specialization, which is enough to get rolling. You can always invest more karma if you decide you like it; the key is to recognize that with Binding, more Binding = more bang per nuyen, not more bang. The reason is that you really don't want to bind spirits with force higher than your Magic, because they can get lucky and roll enough drain to instagib your 3 body pixie.
Dodge is not as good as you think. Most people overrate it - basically, the problem is that in SR, offense > defense. Dodging by no means prevents you from getting hit, and it eats actions. It also won't protect you from everything, many attacks bypass Dodge. And once you dodge, enemies can just switch targets to someone else. It is not worthless and is the right move sometimes (typically, as a mage, the sometimes is when you KNOW that you are going to go down for sure, and then you just blow through actions Dodging to make your opponents waste more actions dropping you). It also adds to passive melee defense. Here, I would either start with 4 dodge or 0. This is a good thing to compare to buying that last point of Body - you can spend 25 bp buying body 3, or 16 buying Dodge 4. To get the other one with karma costs 15 for that third body point, or 22 karma for Dodge 4 - note how the costs almost reverse! And karma is typically worth about 2 per bp.
Perception: 0 is bad, you have to make Perception checks often and you don't want to default. More is better. I would start with 1 or 4 here.
Infiltration: you don't want to be the worst at Infiltration. Being 2nd best rather than 3rd best is not worth your points. Being best is worth your points. Depends who else is in your group - but here, I would consider starting with 0 and buying a bit with karma, since as a pixie with 6 magic people are at -6 to see you anyways, so you are probably alright just defaulting on Infiltration for a bit.
Assensing: You can't default on this and some problems require you have Assensing. You should have at least 1. More is useful, but not as useful as the first point - you need to be able to consistently get 1 hit on assensing, or you aren't able to do your job. Being able to get more hits can get you useful information. Start with 1 or 4.
Illusions is fine as a specialization. It is very all or nothing, so absolutely be sure to have a Mentor with +2 Illusion. If you can't do illusions well, you can't do them at all. Physical Mask, Improved Invisibility, and Trid Phantasm are all really good spells that every Illusionist should have, but there's a very sharp dropoff in good spells after that. There's a line of AE "gives a penalty, might incapacitate people who get a penalty > Willpower if the GM feels like it" line in Street Magic; I would ask your GM how they plan to run those spells and consider using one of them instead of Stunball/Soundwave. There's a lot of super awful illusions that are only good for giggles like Chaotic World so don't feel like you need to load up on bad spells just because you are an Illusions specialist - stick to the good stuff.
The selling points of Charisma are:
More bound spirits
Can branch into being decent at social skills.
Do you care about those things? If no, dump charisma and be Intuition, because it is cheaper and you are short on points.
FFBA is from Arsenal. It is a no-brainer armor that everyone wears, because it counts as 3/1 for encumbrance but is 6/2, and stacks with other stuff. Get some.
Holowear is from Attitude. It's armor that projects a hologram around you. It's easy to tell that it's a hologram (it's a Threshold 2 perception test) but that doesn't mean people see through it, just that they see it is a hologram. You probably don't want to advertise that you are a pixie all the time, so it can be handy for putting up a hologram that makes you look like someone else. Physical Mask is better, but you have to sustain that.
You should also look into Ruthenium coating some armor for the -4 to see you, giving you a total of -10. Stack that with a Concealment power from a spirit and you are pretty much invisible which is cool.
