RRSP Limit

If someone income is $100,000 in 2024, then his RRSP limit for 2024 will be $18,000 (18% x $100,000)

My first question if he already contribute $8,000 in June 2024, does that mean he still have $10,000 that he can contribute in January 2025?

Second question, when he does file taxes next year in 2025, can he claim $18,000 to reduce the taxes?