I'm trying to make a commander deck with Niv-Mizzet Reborn and it is proving to be challenging.

Niv lets you look at the top 10 library cards and pick one card per two color pair, so I'm trying to have roughly equal cards for each pair. The main strategy is to search/mill out General Ferrous Rokiric and then make a bunch of 4/4 guys to attack with while being controlly with instants and sorceries. Other features are:

1. 2 color blink spells, either repeatable or instant speed. Such as Abuelo, Ancestral Echo and Soulherder. Repeats the niv tutor ETB
2. Lord of the Nazgul and Judith, Carnage Connoisseur for more token production.
3. Tutors for Rokiric such as Ringsight and Perplex (3 mana transmute)
4. MDFC dual lands that can be tutored by Niv
5. Spell-slinger accellerators like Rashmi, Eternities Crafter and Prosper, Tome-Bound and Lilah, Undefeated Slickshot
6. Other payoffs like Kalamax and Arixmethes, Slumbering Isle (12/12 that is ramp until you play 5 spells)

Questions I have are:

1. Do I need more unconditional draw to draw lands, mana rocks, and other mono-color cards?
2. Should I also include cheaper payoffs like Witherbloom Apprentice (I gain 1 life and opponents lose one life per instant/sorcery I cast)?
3. Is having unlimited hand size a priority, and if so, will it make me the arch enemy?
4. Is this deck too slow? Typically it's producing creature tokens by turn 5 to 7.
5. Rokiric has hexproof from mono-colored. Is that enough to protect him alongside having blinks available? I have some creature yard recursion in case of forced tributes.