Re: “update your permalink structure” Message
If you are on wordpress, yourposts/pages will have pretty permalinks, like yoursite.com/category/post-title-name instead of yoursite.com/?p=12433 etc.
It is better for you as will give you better SEO and for BP It is required.
Just change the permalinks from numeric to something else.
And as far as I remember, all your posts (previous link) will also function without any issue.