Gerry, I'm an over-self-educated newbie... Here's my thoughts.
When transferring from primary to secondary or racking to a new vessel and the need for adding additives is present first maybe pour a cup of the must into a container and mix your ingredients in this small amount. Next pour this mixture into the receiving container. Then siphon the large volume of must into the container. As it flows into the receiving container (and on top of the must/addtive mixture) the additives will get dispersed pretty well throughout the must. I've seen this referred to as "
racking onto" the addItive(s).
Shaking a 5-gallon glass carboy sends chills over me. There have been some bad incidents with broken carboys cutting people. Be careful!!!
As for siphoning... Be sure you have the full container a foot or two above the empty container and that you have sufficient tubing to hold enough wine in the lower part of it to create a siphon/vacuum action. I sit mine on a kitchen counter and the receiving vessel on the floor. The "weight" of the wine in the tube will pull other wine behind it. If that makes sense.<grin>
I would highly recommend getting an auto-siphon. They are simple contraptions but oh so handy! Not expensive, either. Also, a bottling wand is handy, too. Naturally the wand is really good for bottling, but you can take the tip off of it and use it as a straight cane for putting the tip where the wine will be coming out directly at the bottom of the receiving vessel...and you don't have to fight with a curving, un-cooperative plastic siphon tube to get it to stay at the bottom.
Do you have or will you be getting another carboy to rack into later or will you be racking back into the bucket, clean the carboy, and then rack back into the same carboy? Another carboy makes things much easier. Later, if you do get another carboy, if you decide you want to make even more wine then you'll only need one more carboy to do two batches at a time...a total of three carboys. One carboy to rack into, wash the dirty one and then rack the other carboy into it...a rotation pattern.
Anyhow, that's my take on things...right, wrong, or in between.
Best wishes,
Ed