Using F+1 sets the transmitter output power level (5 watts, 2.5 watts, 1 watt). They call it the "Power switch" in the manual; but that term usually refers to an On/Off power switch.
The manual uses the expression "Frequency deviation" to mean the Transmitter Frequency Offset (for use with repeaters). This is the automatic frequency shift (such as 600 kHz for 2m FM repeaters) applied to the transmitter. The term (Frequency) Deviation is usually used to refer to the magnitude of the modulation in FM transmitters.
NOTE: The bandwidth control (Wide versus Narrow) is F+0+7 and it appears to affect receive bandwidth (?), and transmitter deviation. The manual mentions both "25 kHz" or "12.5 kHz" (receive?), 16K0F3E and 11K0F3E (16 and 11 kHz transmit bandwidth), and 5 kHz or 2.5 kHz transmit deviation. See manual pages 12 and 32.