Are you expecting to connect it to an R232 port on something? If so you will need a voltage converter like a MAX202 or similar.
I also assume that the processor has some software to drive I2C lines, it is shown connected to the SPI lines here, this is the same on some processors but not all. You also need pull up resistors on each I2C line, if Vcc is 5V then 4K7 will do.
How are you making the battery 5V?
I suspect that the crystal on U2 requires a capacitor to ground from each side.