I'm by no means an authority on anything electronics, but I have done some IR projects and I don't think that circuit will work at all.
That won't receive anything at all. You need an IR detector, not emitter for the receiving end. Look for a Vishay TSOP IR detector. It is cheap and easy to work with.
As far as the Vforward and the mA.....
Not sure about forward voltage, I think that it's usually a little more on IR leds. The mA is usually pretty beefy to enable good range. I think the ones I used could take something crazy like a 800mA BURST (as in just a low duty cycle "on" time).
I've never used it for range detection, but I think the idea here would be to use two 555 timers, or one 556 timer. One is for generating the carrier frequency (say, 38Khz depending on the receiver) and the other is for the modulation. If you don't modulate it that the receiver (TSOP) will greatly attenuate the signal. The idea is that you transmit it in front of the device and the IR will bounce back to the receiver -- detecting an object. You use a potentiometer to essentially make the IR transmitting circuit less efficient. I think you can either use it on the carrier wave 555 or the modulating 555, but I'm sure one is probably more proper --- I'd guess the modulating 555. Thus, this will (should) change how well the receiver receives the IR bounce back.
Clear as mud, right?
Also, check me against some other folks by looking at a tutorial on this.