To answer your question about maturity: yes. The Altmer's aging process only slows once they reach psychical maturity. As for the race's average lifespans, that depends partly on magic. The more adept an individual is at magic, the longer they live. Nobles also live longer. Here's the average lifespans (without magic or nobility) of the races:
Orismer: 30-40
Imperial, Nord, Redguard, Khajiit, and Argonian: 70-80
Breton: 90-100
Dunmer: 150-500
Bosmer: 200-600
Altmer: 500-1,000