Trading plan is basically your strategy. In every plan, back plans for unexpected incidents should also be considered such as contingency plan. Taking note of the market distinct characteristics such as unpredictability and volatility. No fixed strategy for daily trading, it is always "it depends on the situation".
Right. Be flexible. As long as you know what you're doing then any plan would be okay. Having a plan beforehand lessens your tendency of being emotionally drawn, which is one of the reasons why traders get frustrated.