Good work so far mate. It's probably better to gently rub-down that metallic surface, and re-paint as required. Metallic paints have a tendency to leave 'clumps' of the metalizer pigment if you try to strip it using any form of paint stripper/remover.
For the small gaps/joints, Venganza's solution is good. You can either use Micro Kristal Klear, or PVA adhesive, which is more or less the same thing anyway. Anthor way is to mix clear varnish and talcum powder. In this case, as the gap is fine, Johnson's Future, mixed with the talc to form a thin paste, would be fine. Just brush it into the gaps, wipe off any excess, and leave it to harden, which should take about 30 minutes. There will be a white, chalky depoist left, which should just wipe off, and any sanding should be minimal. This will give you a permanent, rock-hard filler and joint.