Slash and no slash in an inbound link to your root canonical url (generally your home page) shouldn't be an issue, because Apache mod_dir should add the trailing slash at the root. Both http://www.example.com (without the slash) will resolve to http://www.example.com/ (with the slash).
Try these two links and see that in both cases the home page is resolved by the url with the trailing slash....
If your server isn't set up that way for the root, I'd either make adjustments or change hosts. The trailing slash setup for directories is usually done, btw, in a server config file, not as a 301 in .htaccess.
Generally... and again, this is only for a link to the default root domain... I usually use a slash at the end in the link code, because, as I understand it, this saves the server one step. Again, as I understand it, the performance difference is not significant if you leave this slash off. I'd submit whatever the directory seems to be using.
And, for the default canonical link, varying anchor text patterns for the search engines, slash or no slash in the visible anchor text should not be a concern. Worrying about this is splitting hairs. The engines are looking for unnaturally repeated keywords in the anchor text.
http://www.example.com/index.html , though, is a different creature entirely, and we'll get to that if I don't run out of steam.
More on trailing slashes before that...
Trailing slashes definitely can make a difference in urls when it comes to pages other than the top root, and how they resolve will depend on server setup. While that's beyond the original question, in light of the discussion here it should be mentioned....
Whether or not you use the trailing slash in your link depends on how the site is set up. It generally matters the most on sites with extensionless filenames, or on sites with pseudo-directories, where you can't rely on the engines to sort out the trailing slash and the lack of trailing slash... those are two different urls... and you need to do a rewrite.
The best discussion on WebmasterWorld that I've seen on trailing slashes is in the Supporters Forum, accessible if you're a subscriber...
WordPress SEO Basics
The best single post on the topic I've seen is Jim Morgan's post in this discussion, the New to Web Development forum....
Do search engines care?
The question of index.html is also a long discussion. I'd look at g1smd's post, which I'm referencing in my link, in this discussion....
Home Page Still Not Coming Up in Google - has anyone fixed this?