The springs will not fly out if you open up the hub. The hard part is that the ball ring can be difficult to remove on some of the hubs. You do need to be careful about the hairsprings if you take it apart, but that's later in the process - well after the hub has already been opened.
http://www.sheldonbrown.com/sutherland/CB-IGH-4-aw.pdf
I only open them up if the hub resists a regular cleaning and re-grease (without opening it up). I clean the hub by inundating the hub with WD-40 until the WD-40 starts running out the sides. Initially the WD-40 will be dirty. Keep pumping in WD-40 until it starts running clean out the sides. This may take quite awhile and you will need a basin or some other place to do it. It's very, very messy. If you have an older hub, you can mix in some acetone into the WD-40 for de-greasing any old grease that people have added. Later hubs use a plastic clutch spring cover, so no acetone on those. The metal ones from earlier are OK to mix in the acetone with the WD-40.
After this, make sure the fluids have run out of the hub. Loosen the ones a bit and drain it if you have to. Check to see if the hub is running better. If it's still gritty or really slow, you have to open it up. Use the link to Sutherland's manual above.
If the hub is now running much better and is not gunked up anymore, then you don't need to open it up. You need to grease and reset the cones. Grease on the cones is OK - it acts as a seal for the oil in the center of the hub. Grease in the hub center is bad - you want light oil in the center/transmission part. Once you have greased and properly set the cones, you add 20 weight oil to the transmission.
Sometimes I know up front I need to open the hub up because it's completely caked and filled with grease and junk. I just open those straight up. If it's a borderline case, I wash out the hub with WD-40 as above and then see how it's behaving after washing it out.
Sometimes you need to open it up, sometimes not. If I open them up, I clean them by hand with a rag to remove all grease. If things are really bad, I subject the caked parts to an ultrasonic cleaner. But it's almost never THAT bad.