1. Why tags not separate-able by commas like in wordpress, it would more convenience to seperate phrases...
2. Google doesn't like dublicate content i suggest to add in new version feature tu turn on noindex tags and/or categories pages (.../tag/...)
1. If you separate tags by commas then the commas are removed anyway, so what is the problem here? e.g. 'seo,q2a' should get 2 tags, 'seo' and 'q2a'. No different to spaces.
2. You are misunderstanding duplicate content. The tag/category pages are not duplicate content. However if you want to block them use robots.txt because that is a better method.
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