Well there are many qualities - Those are just painted, no epoxy, no ceramic. On the cheapest ones, I can get the coating off with my nails. I am not doing anything special drilling them in and the wood is not specially hard.
the star drive exterior screws sold at HD are great to use and you can get a box of 25 lbs for under $100. using stainless will be even better though and you already have the screw holes established from the previous screws so cam out will not be to much of an issue with the stainless screws. Drive them in slow and steady and if they bind up reverse back out some and then drive it in again.