Building two handed piano scale exercises.

Disclosure; I am a rank noob at MuseScore.

I'm trying to build some custom scale exercises for PianoMarvel (PM) software. It supports musicxml and midi imports from Musescore, Finale, and Sibelious. Obviously, i'm using MuseScore (MS). I do understand that this is not a PianoMarvel support forum, so i'm not asking for help with that software. I'm trying to get the right output from MS so that i get the correct appearance and functionality in PM. I am trying to build consecutive, two hand, two octave scale runs in major scales. Picture 1 (C Major) is what the first six measures look like in an existing CGF scale, chord and arpeggio exercise in the PM software. After these six measures it does the same combos (two handed two octave scale, chords, and arpeggio) in G and then F.

I am doing this because i want to eliminate the chords and arpeggios and do the 3 scales (CGF) back-to-back. I will also want to do this for other Major Scales and Minor scales as well. So it's worth learning how to compose this correctly in MS. Pic 2 (C Major MS) is the first two measures (C Scale) i have built in MS.

I read up on using voices to get the right hand tails to go up and the left hand tails to go down. The problem with voices, is that i now have rests in voice 1 in the bass clef, and rests in voice two in the treble clef. Though i can delete the voice 2 rests, that screws up the score once imported. I can't delete the voice one rests (i read it and I get it, music is either sound or silence). So, i hid the rests in voice 1 and 2. But they still show up as visible in the musicxml file that gets exported and then imported, see picture 3 (C major MS import.JPG).

As you can see the rests make the display of the exercise quite unruly and messy.

Other than the rests being displayed, however, i'm happy with the output.
The line break works as described here: https://musescore.org/en/handbook/3/breaks-and-spacers
The voices get the tails in the right direction as described here: https://musescore.org/en/handbook/3/voices
So i think i'm going about this in more or less the right way.

The only reason i'm using the voices is to get the tails pointed the right way. I've only gone as far as the C sale at this point, because i don't want to have to redo everything after i figure out how to do it right.

Questions:
1 - Am i approching this problem in the correct way? Two voices even though i'm really only writing for one voice, the piano?

2 - If this is the correct general approach (one voice for left hand and one for right hand, simply to get the tails to display correctly, is there a way to hide the rests so they don't show up in a musicXML import?

3 - After i tackle this problem i will want to change the key signature for measure 3-4 and then again for measures 5-6. Will that be a problem?

4 - Does anyone know if I can download already built scores of two octave major and minor scales in museScore?

Thank you for any help you can provide.