I used a Mitivac to pump out the majority. Just insert into the rubber plug once removed on the passenger side of the trans and you'll get the majority. After that there will be very little fluid left in the pan once you drop it.
As for the exhaust y-pipe... it's not really that big of a deal. I don't use the jack or strap method. I just lie on my back steady the pan with one hand and use a pry bar wedged between the y-pipe and the cross member. You really don't need to move it much at all to clear the pan... I had no concern with stressing it. You're really not moving it much at all. You'll see it makes sense once you're under doing it.
Once you get the pan off you can do the normal cleaning of the pan and magnets, check gasket (I just replace regardless), change filter and put it back together.
One note... if you haven't replaced your trans temp sensor just order it and do it since you're already in there. It's a simple replacement. You need it to be accurate to ensure proper fluid level check temp range. Mine was acting up so I just replace it since I didn't want to drop the pan again.
Once you're done and have everything buttoned up, I just pump in the new fluid using the same rubber plug port on the passenger side.
The biggest thing with all of this is to set aside the time and don't rush it. It's not hard but time consuming and procedural.
Side note, I received an extended warranty bulletin from GM a while back regarding the trans temp sensor replacement. You may want to check with your dealer if it applies to your vehicle. If it does, they'll replace the sensor under warranty. Which all means you get a free fluid change
That being said, I'd trust it more doing it myself and then just having them reimburse for the part which they'll also do if it applies to your vehicle.
Hope all that rambling helps.
