As a general rule of thumb I would think the aircraft makers don't give out data, the data and etc. are not magic or anything they want to keep secret, it just makes life easier for them to not to have to respond to those kinds of questions.

I don't know if this counts as my building anything but I have been involved with wind tunnel tests of several fighters that used spoilers (the model shop made the models for us, a good way to work). I am a safe person to have seen the data as I have forgotten most of it! Old age brings with it wisdom (sometimes) and forgetfulness (fairly often).

As Tall Paul said they are usually put on a wing station just ahead of the hinge line of the ailerons. Most things in life are a compromise and this tends to be one of them. Although they might be effective at other stations they certainly are effective enough at that location, It is used by everyone so you might as well go with it.

At low deflections you can think of them as an aileron that just goes up. Of course the flow separates but it is no big thing. I think the delay in spoiler movement you mentioned is due to that the initial control is input with ailerons for small precise moments and minimal aero disturbance (you will get some of course). As you need more you bring in the spoilers to get more rolling moment. The drag goes up and other stuff happens but you usually need the roll more than the side effects. I remember sitting at the window seat on an airliner and watching the movements of the various stuff during flight and landings maneuvers. Very educational.

It would be interesting to see the layout of the wing as to precise locations that you use.

A good drawing or plastic model of a Boeing airplane would give you a layout of the spoilers and ailerons. It may be on the net.