Yes you can lock the safety off. The instructions are in your manual. There is a small pin supplied with your gun. You have to take the stock off and insert the pin into the safety mechanism to lock it out. I do not know of any way to lock the barrel selector. I have two F3 Super Trap Combos, one for my wife and one for my grandson. Great trap guns.
There is No way to lock the barrel selector as it is hard to move and will not cause a problem. I have never had mine change unless I wanted it changed. My safety is locked off though. One of the first things that I did when the gun was new.