For most booking sites (Airport and Hotel) use SEA.
SEA is the airport code
SEA
The standard abbreviation is "assoc."
Decl. is the standard abbreviation for "declaration."
The standard abbreviation for height is ht.
I don't think there's a standard abbreviation of "following" but we are used to using "ff." as the abbreviation of it.
No standard abbreviation
This abbreviation is Fr.
The abbreviation of weather is W.E.A.
The standard abbreviation for California is CA.
The abbreviation for "Place" is Pl.
The standard abbreviation for Skopje is SK.