When dealing with the electronic ballasts, there are problems with mounting them remotely, namely, 2' ~80cm is the max distance you want to mount the ballast from the bulb because of increased capacitance...
Advanced Transformer has some good information on their electronic ballasts... which I believe is owned by Philips lighting, NAM etc...
http://www.advancetransformer.com/uploads/resources/2006-07_Advance_Atlas_Section_2_Electronic.pdf
But the most useful page was the bulb manufacturer, USHIO, spec page for their CFL bulbs...
**broken link removed**
It has the operating voltage and current rating for various biax (2 pole) or other multi tubed CFL bulbs... so you can presumably determine which ones have the same voltage and/or current to operate...
The general understanding I have is that tube length determines compatability... meaning a bi-ax 2 tube bulb of 18" length = 36" total length, will generally run on the same 36" tube T-8 electronic ballast...
But I have no idea how some ballasts will run different length bulbs, can anyone explain that? I bought a couple dimming dual 24w Advanced transformer electronic ballasts on ebay for silly cheap, and it says it will run 18, 26, 32, or 42w bulbs... the current ranges from .220 to .320, and voltage from 100-135v respectively... so not sure how it auto-selects?
Electronic Metal Halide ballasts are terrible if you mis pick the bulb to ballast... for example the 150w bulb has 3 different voltage specs, the older versions ran a higher voltage, but some of the newer ceramic bulbs run a lower voltage, but pulse start... which meant basically it couldn't ignite the bulbs, but eventually the bulbs would explode because of overvoltage across the arc tube... I don't think that's a problem with CFL, but just saying specifying the wrong ballast for the wrong bulb can cause rupture... so be careful.
Ebay is your friend, I ended up with 4 of these dimmable ballasts (normally 50-75$) for 10$ a piece, 4 bulbs for 8$ a piece 42w, 4100k, 82CRI, and 4 sockets all for about ~100$, ~25$ a piece... for 80 lumens/watt light source. These are instant on supplements to my Metal Halide 100w bulbs I have in the rooms...