The fact that you use a shoelace is worrying, you don't want to risk brain damage or paralysis, even if you do partial suspension there will be a lot of strain put on the shoelaces. I wouldn't use a shoelace for hanging myself, but if you are absolutely sure that it won't break then you can use it.
A snuggle hitch seems like a strong and secure knot in itself, so for the horizontal bar it's a good choice. But it doesn't seem like the type of knot that tightens under load, so I wouldn't use it for your neck. If you're doing full suspension this won't be a problem and a snuggle hitch is fine even though a slip knot is more effective, because the ligature will stay in its place on your neck. But for partial suspension you need a knot that tightens under load (like a slip knot). You don't want a noose where the knot is already strong and secure in its place, the opposite in fact, you want a knot that can slide through the noose under pressure so it tightens itself. If you use a snuggle hitch for partial suspension, the act of simply moving your head will put less pressure on your neck, think of how reliable a snuggle hitch will be when your body moves uncontrollably (and it will).