You can try smoke=0 but it might just default to another smoke. If you have an idea/question for such a simple change like that it's much faster to take 15 seconds and try it than to ask on forums
Assuming it does not work and you are not using a really old version of FPSC, do the following to remove smoke.
1. Go to your decals directory and make a new decal and call it "null" (or whatever you want). Edit the actual image for the decal so that it is small and has no valid image content (100% alpha).
2. In gunspec, change the line which says:
smoke = x
to
smokedecal = null (or whatever name you chose).
Alternatively, if the .x file is in an uncompressed/text format, I'm fairly sure you can search/delete all references to "SMOKE" and be rid of it.
To remove automatic fire (on most full-auto weapons), simply comment out the line which reads:
automatic fire = x,y
That should leave you with
start fire and
end fire resulting in semi-auto firing.