They don't need to be "familiar with Lightroom", they'll just be using a browser to view the images in the album. They can scroll through the grid of image thumbnails, click on a thumbnail to view it in the full browser window, or click on the slideshow icon to view the album as a slideshow. Other controls may be available depending on the share settings that you are using (e.g. the ability to download jpegs of the shared images). But there's nothing difficult about that at all.
No, not at all. That's the beauty of the Lightroom album sharing feature....any changes you make to the album content (edits, new images, removed images) will be seen by anyone who has the shared link (they may just need to refresh the browser window after you make changes if they normally keep the window open in the browser indefinitely).