Sine wave Code OR Sweep Code to Servomotors

Hi friends,
I have to generate insect flapping motion to my servomotors. Let say flapping frequency (1hz, 2hz, 3hz,4hz 5 Hz) and flapping amplitude (i.e up and down motion of the wing: -90 to 0 to 90 deg.).

Seems I have to create sinewave to my servo (at certain frequency with flapping amplitude)

In this context, I used sweep option in arduino. pls see the two code below.
Q.1) Can someone explain the difference b/w these codes?

Q.2) Helpful if someone guide me how to create sine wave motion (i.e insect flapping motion (up & down) with certain frequency)). Thanks in Advance.

Code.1
#include <Servo.h>
Servo servo1;

int servoPos =0;

void setup()
{
servo1.attach(9);
}

void loop ()
{

for(servoPos = 0; servoPos < 180; servoPos++)
{
servo1.write(servoPos);

delay(10);

servo1.write(180);
}

for(servoPos = 180; servoPos > 0; servoPos--)
{
servo1.write(servoPos);
delay(10);
}
}

Code.2
#include <Servo.h>
Servo servoMain;

void setup()
{
servoMain.attach(9);
}

void loop()
{

servoMain.write(0);
delay(1000);

servoMain.write(90);
delay(1000);

servoMain.write(180);
delay(500);

servoMain.write(180);
delay(1000);

servoMain.write(90);
delay(50);
}

Can your servo swing fast enough? What is it's rotation speed? Typical is around 120 milliSeconds for 60 degrees, or 360 for 0 to 180. Which servo?