"ST A" is a command to control any of the 8 Modulator (to my understanding "ST A"..."ST H" are essentially the same commands - which modulator is doing what on which output is completely determined by the parameter of that command, i.e. "ST A" "0004" and "ST H" "0004" are essentially the same commands).
The Modulator could be one of several different types of envelopes or an LFO. By giving the parameter "0004" you indeed do start/continue the LFO of Modulator 1 on CV 1 of this CV16 NSA.
With "SLFO" you could set the various attributes (Speed, Waveshape, Amplitude) of the chosen LFO.
What do you mean by "moderate speed and amplitude"?
I haven't used these LFOs in a while but I recall their settings where slightly different from what I had been expecting. In particular I had struggled to consistently determine or even align the exact speed and frequency of the LFOs w/r to the BPM of my track.
I seem to recall Thomas had done some work on the LFOs and I have revisiting them on my TODO list.
Try setting the parameters to extreme values and see what they are doing. They used to work
To explicitly answer your final question:
LFO1 on CV1 is the result of "ST A" "0004". "ST A" "0104" would by LFO1 on CV2 and "ST A" "0314" would be LFO2 on CV4.
[Strictly speaking it is not "LFO1 on..." but "Modulator 1 acting as LFO on..."]
Kind regards,
Michael