I signed a one year rental lease, if I move in 6 months, will I have to pay the full amount?

The Landlord has a duty to mitigate, or minimize, its damages by attempting to get a replacement tenant. If it can't get a tenant, or if it gets a tenant who pays less than you pay, you would be liable for the difference. If you have decided to move out, give the Landlord as much notice as possible and keep a copy of the letter.

You may. However, you should review your lease with an attorney to determine what exactly you may be liable for. Some leases have early termination fees. Others do not. You could be liable for the remaining 6 months. Bear in mind, however, that under Washington law, a landlord has a duty to mitigate damages, which means the landlord must try to re-let the premises, and if this can be done before the 6 months run out, you might only be liable for a couple months instead of the full 6 months.

Would have to review the lease. You can try to cut a deal with the landlord or perhaps sub- lease.

Landlord has a duty to mitigate (re rent the property) so you would be responsible until it get re-rented.