DLLからのメソッド呼び出しとかフォーム表示とか

Assembly asm = Assembly.LoadFrom("AAA.dll");
Type t = asm.GetType("NameSpace.NameSpace");
MethodInfo method = t.GetMethod("ABCMethod");
using (Form frm = (Form)asm.CreateInstance("NameSpace.NameSpace"))
{
method.Invoke(frm, parameters.ToArray());
frm.ShowDialog();
}