I used Pittman's One Step to clean mine last year and they still look good. I did not need tools or protective clothing so I'd say it was pretty safe and its liquid, so its safe on the headlight too. Absolutely no abrasive damage.
There is a kit you can buy at the auto parts store to take that off headlamps. Ask at the counter and they should be able to point you in the right direction.
I understand there is a product at motorcycle places like Harley's that have a product for the motorbikes that is excellent to clean the headlights. I don't know the name, but I'm sure you can ask and find out.
Whiting* sprinkled on a damp (non-abrasive) cloth should remove the foreign particles and polish at the same time. Not knowing what material your lens are made of, if High-impact Acrylic, it should have UV properties within; if still concerned after cleaning your lens, apply a UV Protectant available from an Auto Wax..
*Whiting is available from your Paint Dept in a good Hardware Store...
Meguiar's "Mirror Glaze 17" can remove hairline scratches from Acrylics & Polycarbonates (as well as from my Casio Watch face :)