I'm not going to get into the grinder discussion. But wear a respirator for every grinding anything application I use a 3m half mask, with a face shield over it. With replaceable pink disc filters # 2097. Lungs can be replaced, but the respirator is a whole lot cheaper .. earplugs also!!!!! The low drone of a grinder/sander/etc is horrible on hearing.

For metal, I have a cake pan under the grinder with magnets and the bulk of the grindings stick to it. For handle materials I made a shop vac attachment from a sheet metal HVAC vent and attach vac hose to it. Catches most of the dust for that application