Glad you got several programs set up. Keep up with the management so that you can keep the phone's internal storage as freed up as possible, because it's finite.
BTW, I don't think the programs that are stored internal to the phone reside in RAM. If they did and you removed the battery, they'd be gone. There is an internal non-volatile storage as well as RAM.
It's likely there is a bit more to building an application to provide the ability to be moved to the SD Card and run from there. Also, I'm not positive about this, but, some apps were engineered probably before the OS supported putting apps on the SD card. I believe I have witnessed cases were a program I was using couldn't be put on the SD card, but following an Update, the feature was there.
There may be something to the other poster's comment. If the SD Card is slow (the class of the card), and if that program is large or complex and has to move many bits, it might slow things down somewhat to be transferred off the SD Card and into RAM to start running. I use a class 6 speed microSD card, and I can't really tell much of a difference.