To become a member of a US political party, you can list or check your party preference when registering to vote. Alternatively, you can call the state or national political party office to be added to the membership list.
Social Democratic Party which is the oldest political party in Germany; the Christian Democratic Union; the Christian Social Party, which is the sister party of the CDU and is confined to Bavaria; the Greens; the far-rightist, The National Party; and the "new" Communist party of Germany.
No it is one of the oldest. It was founded in 1891 and is the oldest existing political party in Australia. It also predates the Labour Parties in the UK and New Zealand in both formation and forming a government.