Re: Making multiple melodies line up with harmony.
This post assumes you know basic music theory (i.e. scales, chord inversions, and the like). If you don't, do a little bit of research and you'll pick it up pretty quickly; it isn't complicated (IIRC there's a music theory guide on idmf someplace). If you don't know music theory, your ability to compose music period will be seriously stunted. Just do yourself a favor and spend a few hours learning this.
Okay, so make yourself a melody. The melody should be in a 2:4, 3:4, or 4:4 time signature; at least if you want to make it easy on yourself. Also, have the melody be in a specific key. Now, at semi-regular intervals (once every 1/4th note or 1/2th note, mostly), 'map' a chord onto your interval. Basically, make a chord every 1/4th note or whatever so that you can play both the melody and the chord sequence at the same time, and the piece will sound good. This isn't as hard or arbitrary as it sounds: if you have one of the chord's notes be the same as the 'important' notes in the melody-segment it corresponds to, then you can build a chord around that. For example, if I used C as one of my notes, there are several chord options I might try: any of the C major or C minor inversions; any of the Diminished 7ths in the keys of C#, E, G, A# (to find the diminished 7ths of a key, find the note a semitone below it as the 'base note', and then every 3d semitone above that base note: for example, the root diminished 7th chord in the key of C# contains the notes C, Eb, Gb, A.); the major 7th chords in the keys of C#, F, G, Bb. Obviously you needn't restrict yourself to only these, but they provide a great starting point. The chord sequence also should contain some tension/release and variety. For example, following a C major chord with a major 7th in the key of E, then an F minor... standard major/minor chords make good releases, while grungier ones like diminished 7ths add lots of tension.
Now that you've got a chord sequence, you map a melody onto that the same way you mapped a chord sequence onto a melody. Just make key points in the melody match up with one of it's corresponding chord's notes. Hey presto, you've got counterpoint, plus a chord sequence you could use for pads or the like. It all requires practice, obviously, but it's also not rocket science.
You should also look into phrasing and call-response. Basically, if you follow one little phrase/lick with another that answers it, you've got a great melody/chord sequence right there. For example, in the second track you posted, the phrase at 0.39 'answers' the phrase at 0.36. You'll find call-response in most good music; they're especially noticeable in Hardstyle melodies.
There's obviously lots more, but I'm out of time for now. If you've got any questions, just ask.
I hope this helped!