I think you have some great ideas there; multi-sensory activities are definitely the way to go. And keeping each item fairly short helps with attention span problems. Avoid long explanations and rambling sentences; folks with short term memory problems need short, direct sentences and closed rather than open questions. There is lots of info on the Alzheimers Society website to help you understand some of this kind of stuff about the usual effects on people's functioning.

People with dementia type problems lose some inhibitions so be prepared for the possibility of powerful reactions. You can't predict when something you have brought in could have deeply personal associations for someone. I second the advice that you should ensure that staff are in range; you are there because of your entertainment skills and not for tackling care tasks.

Trust your creative and human instincts; you clearly have much to offer and it will be good to hear more from you.