I use mini lyrics and embed the lyrics, there's nothing wrong with embedding. I prefer keeping everything in one file, but you can do both if you want backup.
I think minilyrics is still the best source for automating lyrics retrieval in general, and the only real source for synced lyrics. No matter what source you're using there are always some mismatches, but it's not like it's hard to fix when you find it.
Honestly, lyrics are pretty easy. Much easier than artwork, lol