Just learn the notes. Patterns are especially great for practicing technique and aural training. But when you're in a band situation discussing music is much easier with notes, chords, etc.
A sequence is a progression of notes or chords which mimics a previous progression. So if I were to play E, D#, B, A#, G#, B a diatonic sequence would be F#, E#, C#, B, A#, C#. As it's the same pattern of intervals but starts on a different diatonic note and follows the diatonic scale. So rather than being in the lydian mode it's in Mixolydian. At the same time however you can copy the previous sequence exactly borrowing notes from a different diatonic key. In which case the notes would be F#, E##, C#, B#, A#, C#. As it mimics the intervals exactly using a different key, but the same mode (lydian).
That may go over your head, feel free to pm me if you have any questions, or go out and buy some music theory books that have passages on sequences. There are a lot of books out there that are much better at explaining things than I am. And have much more information than you'll ever really need.
As far as popular metal scales. Anything with a minor third is common as well as altering scales to increase number of dissonances.