要是想学的话，建议买个开发板，。。或者说 强力推荐..。。。

第一、二个问题我还没有研究过，貌似网上有很多资料你可以搜索到，度娘一下。。。
第三个问题我用到过，交流下


USARTInit(void)
{
    //模块时钟配置
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);
  
    //io 端口配置
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 ;//PA9 -- TX1
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 ;//PA10 -- RX1
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
   
    //UART 模块配置   
    USART_InitTypeDef USART_InitStructure;
    USART_StructInit(&USART_InitStructure);//设置缺省值
    USART_InitStructure.USART_BaudRate = 115200;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
   
    USART_Init(USART1, &USART_InitStructure);
    USART_Cmd(USART1, ENABLE);
   
    //打开中断
    //USART_ITConfig(USART1, USART_IT_TXE, ENABLE);//发送中断
    USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);//接收中断
   
    //嵌套中断控制器配置
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
    NVIC_InitTypeDef NVIC_InitStructure;
    NVIC_InitStructure.NVIC_IRQChannel =USART1_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
   
}