i believe the yeast reach a point where it's easier to ingest sugars like dextrose. once the yeast has stopped feeding on what you provide it (e.g. after hydrometer readings are consistent), it ain't gonna feed anymore unless it gets something it can eat. plus the fact that the amount of yeast that ends up in the bottles is a small fraction of what was produced/settled during fermentation.
i think the ABV can be somewhat affected by the addition of priming sugar, but at the volumes most use, it will not make a difference... the danger with bombs is when you bottle before readings are the same, somehow restart a stuck fermentation in the bottles, have an infection, or use too high a volume for the bottles you're using.
i THINK you add more simple sugars (e.g. sucrose/dextrose) to dry out a beer and lower the FG, but maybe additional yeast has something to do with that. i think a stuck fermentation is a whole different subject. there, you're just trying to lower your FG to what it "should" be for the style... with drying out a beer, you're aiming to lower the FG further than what it would be with grain alone.
i wouldn't be too concerned about bottle bombs... not to say they don't happen, but if you're good about sanitizing (the dishwasher has worked well for me, no soap, heat dry), and mix the priming sugar well (put in the bottling bucket and rack the beer onto it), and use the right amount (in weight, get a cheap digital scale), you should be just fine. you can put the bottles in a plastic bin if you're paranoid.
sorry, i'm rambling... good luck!