Re: Help needed with connecting Transmissive Optoschmitt Sen
1) Yes. Datasheet says you can.
2) Looking at 'IRED Forward Bias Characteristics' and for temperature of 25°C and about 20mA drive current, the device has a voltage drop of 1.25v. This means that 3.75v will be dropped across the limiting resistor, ie
Rlim = 3.75v/0.02A
= 187.5Ω, nearest value being 180Ω, depending on the application you may be able to reduce the drive current to a lower level.
The cathode should be connected to ground.