When you edit a chosen drum kit, using the Sound Editor, and press WRITE, the 'new' sound is placed in the User Kit. You can save this edited Drum sound to a panel Memory and then to SD Card along with other settings. It can also be used within the Composer Memories and even transferred to Custom Memory if you wish. (Custom Style Copy in the Composer Menu)

With regard to your last question, to display lyrics on an existing sequence, you need to produce a series of JPG images of the words, using your PC - probably up to 4 lines of text per image and these images can then be loaded into the Sequencer system, to create a 'Slide Show'. The procedure is outlined on Page 77 of your user manual.It will require some experimentation to achieve the desired result

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Willum

After silence, that which comes nearest to expressing the inexpressible is Music.
Aldous Huxley