Personally I am leaving as it is and I don't think it's an issue. Wordpress also appends a slash and I know tons of wordpress pages which rank really well. I am also sure they would have changed it if this is an issue.
It's probably the same like the www vs. non-www decision.
Well that is actually correct. It's important to be consistent at this point. I haven't removed the trailing slash because I am worried that the sitemap will report links with a trailing slash and Dr Google may be angry because we have reported a link which contains a redirect.
As far as I know it hasn't. It's common practice to remove that slash actually. Google does that as well, personally I'd remove it and personally I also think this should be the default in IPS.