In HH95 (or was it '94?) then Spaz was a baby, and Jazz was a teenager, so I would think that Spaz is at least 14 years younger than Jazz.

Devan was an adult right from the beginning, and as Janus mentioned, turtles live a long time, so I would say Devan is about 50 (middle-aged for turtles).

Eva would be about the same as Jazz, and the rabbit queen (boss) in JJ2 looks about 50 as well. People usually have kids between 20 and 35 (say the queen and king had eva at 27), so she is 23.

Lori the sister looks closer to Jazz than Spaz, so she is the middle child. Eva also looks slightly younger than Jazz.

Therefore:

Jazz: 24
Spaz: 10
Lori: 19
Eva: 23
Devan: 50
Queen Rabbit: 50

I can't remember if the king is in any of the videos, so I'm really not sure how old he looks, but he is probably about the same as the queen. BTW, does anyone know where I can find that video of the wedding, where Devan crashes in and steals the ring? I know I saw it once, but I've never seen it after that.