Don’t worry TOO much about the weapons that are locked into damage types.
Most of the generic NPCs are, to some degree, weak against Thermal damage (which all weapon types deal (yes, even projectile guns))
And if your weapons have enough DPS, you can punch through anything.
That said, you mentioned having “limited skills”… so you are thinking smart about this. Kudos. 
Drones are, on paper, very good for ratting.
But consider that they are just as intensive to train as missiles, can be shot down, and left behind if you are in a rush to leave an area.
I would recommend taking a step back and start low-sec ratting with a Kestrel frigate.
It may not deal as much damage as a Destroyer, but you gain large speed advantages… which will help when you find yourself being hunted by other players.
Yes, some NPCs may be too tough for you to take on and thus should be avoided… but you will learn much more and be “safer” this way.