I have no hints & tips re edge sanding, other than just go at it. Takes an age!
The middle example above seems to match what remains of your first finish in the neck pocket. Brown seems to cover everything well - it’s what I used on my refinish (used Crimson Guitars stuff);
My only regret with this one was being an impatient prat and not leaving enough time between stain coats, leaving it a touch patchy in places.