But, if I don't have /r/bitcoin +frontpaged already, how is it going to be on my frontpage? /r/bitcoin doesn't even constitute a /r/newreddits post.
Not to be debbie downer, but I don't think reddit works that way. Otherwise NSFW shit would pop up on my frontpage all day.
NSFW stuff pops up on the frontpage everyday! But I confess, I don't know the inner workings of reddit. I assumed any submission, no matter the subreddit of origin, had a possibility of getting front-paged.
By default, NSFW is +frontpaged. If you -frontpage /r/nsfw, you won't get any more from that subreddit. However, there can still be nsfw posts in subreddits you are subscribed to, I don't know if you can hide that.
Newer subreddits get advertised sometimes in reddit's blog post every month featuring cool new subreddits, but there's an arbitrary "group" of default +frontpage subreddits that you are subscribed to upon registration. /r/bitcoin is definitely not one of those.