It may not have enough dill flavor for you. You would have to skim off the dill weed along with any scum.
My suggestion is to wait until they are fermented, then taste one. If it needs more dill, then add the dill before you process them.

It's not going to cause spoilage. Whether the pickles will be sufficiently "dilly" depends on how much you used and whether the final result suits your taste. However, you can always add additional dill to the jars if you want more of a flavor boost.

Scum is normal though whether you get scum or not depends on factors like temperature. Warmer temperatures are more likely to foster scum. You just skim it off with a sterile spoon or ladle. If you lose some of the dill in the process, so be it. Scum is not that worrisome as long as it's only scum and not mold and is removed regularly.

Carol