Using sequelize.js to interface against existing database?

There are a lot of questions in this post, I'll try to answer them all:

Disable timestamps globally:

new Sequelize(... ,{
  define: {
    timestamps: false
  }
});

You can pass any define options to the sequelize constructor and they will be applied to all calls to sequelize.define

Mapping to an existing database

I'll try to describe some common cases here:

I want my model to have a different name to my database table:

sequelize.define('name of model', attributes, {
   tableName: 'name of table'
});

My database columns are called something different than the attributes in my model:

sequelize.define('name of model', {
  name_of_attribute_in_model: {
    type: ...
    field: 'name of field in table'
  }
});

My primary key is not called id:

sequelize.define('name of model', {
  a_field_totally_not_called_id: {
     primaryKey: true // also allows for composite primary keys, even though the support for composite keys accross associations is spotty
     autoIncrement: true
  }
});

My foreign keys are called something different

X.belongsTo(Y, { foreignKey: 'something_bla' });

disclaimer: I am a sequelize maintainer :). Overall I think we have pretty good support for working with legacy DBs. Feel free to ask more questions here or on irc://irc.freenode.net#sequelizejs