1) TSSD makes some German, US, and Japanese firearms, plus supporting weapons (US 81mm mortars and M1917A1 HMGs). For conversions I have been known to "cut and splice" weapons to change its appearance or how it is held.
For the softer, earlier Conte figures (like the US and British paratroopers and the German Army and SS sets) I have found them to be slighty smaller than the Conte GIs/TSSD figures. For the older Conte figures I have been able to use the nice cast white metal weaponry from H-R Products.
When I haven't been totally satisfied with certain weapons (TSSD panzerfaust and StG44) I have been known to use parts of the original weapon and modify them to look better (to my old eyes).