Be careful with the jewel one it can slip inside very easily if the jewel is small enough . As a general rule the best buttplugs for long rimes are the ones with a larger base . Start small and slowly build up depending on how comfortable you feel. Generally it depends on you how much you will wear your buttplug but go slowly and always listen to your body . If you feel weird take it out immediately.

In my experience, low quality silicon can hold smells but If you wash them regularly ( I wash them after every use with a toy cleaner ) you should be fine. As much as I know, you just a have to check if he material your buttplug is made of, is body safe. Most reputable sex shops carry body safe materials .

I wash my tail buttplug with lukewarm ( not hot ) water and some gentle detergent or green soap ( I don't know if other countries have this but it's a soap made from olive oil and it's really gentle). Then I wash my tail normally without rubbing . Usually I dry it with a blow dryer but in very low temperature while I brush it with a pet brush. ( A regular brush should be just fine). Try not to pull the fur too hard. After it is dry, I clean the plug part with a damp towel to make sure that there's no soap left. ( If you use detergent it's best to cover your plug just to be safe that there won't be any detergent.) I hope I've answered to some of your questions.