everyone will start at level 1.
your stats will look like this.
Hp 10
reiatsu 10 both of these get 10 points each, and will each get 10 points a level.
body stats you start with 10 stats points for these, and get 2 every level
strength 3
agility 5
endurance 2
reiatsu control 0
fighting skills stats, you start with 10 stats points for these, and get 2 every level
swordsmanship 3
unarmed 0
kido/cero 0
shunpo/sonido 7
that was an example for a starting character, as you level you will get rank advancements, or if your a hollow, evolutions. you don't have to evolve at said level, or rank up, but you can't do so before said level.
shinigami
lv1 unseated
lv3 seated
lv4 shikai
lv 8 lieutenant
lv12 bankai
lyou can become captain as soon as a spot is open, or if you think you can beat one
hollow
lv1 hollow
lv3 gillian
lv 5 adjucha
lv12 vasto lord
arrancar, whenever you like, although it will stop any further evolution form your character
espada, as soon as you can beat a current espada
also for both character types, there is exp scaling with lv.
lvs 1-3 50 exp to level
levels 3-6 100 exp
levels 6-10 125 exp
levels 10-13 150exp
levels 13-16 175exp
levels 16-19 200 exp