Placing suffix u with unsigned variables

I was reading on misra website that for assigning 0 to unsigned variable, 'u' must be suffixed.

For example:

uint8_t my_cnt = 0U;

1. Does that even on declaring array I should use this.Like

uint8_t my_arr[10U];

2. Also while using switch cases like:

void func(uint8_t no)
{
    switch(no)
    {
         case 1U:
         break;

         case 2U:
         break;

    }
}

If yes then what if variable passed to switch is of int8_t type. In above example if

int8_t no;