Example: Spcaemarine Tactical Squad
Weapons, 1 flamer, 1 Rocket Launcher, Rest bolters

would weapons I give the Vet Sgt count against weaponry limits? Im asking because i was wondering if i give my Sgt of my cadians a Grenade Launcher, would it disallow me to give ne to another guardsman?

sergeants cant take grenade launchersIIRC and if they can it's perfectly legal too have a trooper with grenade launcher heavy weapon and a sergeant with a grenade launcher, but this is the maximum you are allowed [unless it specifcally says otherwise

so, my friends ork mob that I converted (slugga boyz) can still have the nob with the shoota and the mob can still have the 3 big shoota boyz?

yup, the limit on weaponry is for ordinary soldiers, veteran sergeants, nobs champions etc and HQ choices can have any wargear ignoring these limitations

Most like champions of chaos and such can only pay for the weapons open to them... not just anything like a chaos Havoc champion cannot hold another lascannon...

sweet thanks, i just converted a reg. Infantry squad into HV and i let the sgt have pistol and CCW cus i dodnt know that...