Really good tutorial and the template is very helpful!
But I have some questions:
i haven’t watched the theory tutorial so some of this may be repeat information, but a mode is like a re-sorting of a scale’s notes. ionian/major is what modes are based on, so for example C D E F G A B C is in ionian mode / C major. so D E F G A B C D would be D dorian. the intervals, notes and order are the same, but because they’re rooted differently you get totally different feels.
a really good way to get a sense of modes is on a piano. using only naturals, play C → C, then do D → D. you’ll notice how much more minor dorian sounds, and of course aeolian (A → A in this example) is actually natural minor.
because the same intervals are in play, the same chords are in play. that is to say that C Major has the same chords as E phrygian, G mixolydian, etc.
while experimenting with modes you’re going to get different kinds of tension in different spots in the scale. my favorite cadence is the good old authentic V7 → I, which sounds super major. i don’t really stray far from major keys in most of my writing because i love the tension and resolve that’s created from the 7 to the octave. for a more minor sound without sacrificing the major scale i love so much, try mixolydian (even though that takes away my favorite part lol).
in essence, a song’s mode is going to be dependent on the “home” note. so figure out what you’re resolving to, then adjust as necessary. but fwiw i would just choose notes that sound good to your ears without paying attention to what mode they may be in.
lol ok i’m done rambling, i’m sure someone else will do a better job explaining, but i’m happy to clarify anything.