Sad to hear about the attack, glad you're trying to help the survivors.
Storey's Guide recommends clipping the feathers that are around the edges of the wounds.
You probably already have looked very closely around the vent and under the wings, but I will mention that.
A lukewarm bath helps - it helps the ducks feel better, often, and it lets them wash off, and it gives you a chance to watch how they move, lets you scan for signs of injury you may have missed.
Saline solution is a pretty good antibacterial, you can make it yourself, and it doesn't cost that much.
Keeping the wounds away from flies but well aired should help.
If they get an infection, then probably Duramycin would be an antibiotic I would consider having on hand.
Here is a post I have saved with some good details.
Post raccoon attack advice from Captain Cluck BYC DF 20120617
When my duck, Lucy, was attacked by a raccoon, I had head wounds to deal with, too. No jaw damage but she had a bite taken from the edge of her bill.
I put her on homeopathic for bites and vitamins at first, but homeopathics take a long time to work, so after a week on that (and an infection starting in the leg wound that I had missed) I switched her to Duramycin (got at Tractor Supply). Add 1/4 teaspoon to 20 oz of water (2 1/2 CUPS). Only mix up what you will use immediately and store the rest of the powder in a clean, dry jar. You will want to keep a measuring spoon in the jar just for the Duramycin. If you won't be using the entire 20 oz right away, put the extra in the refrigerator until you need it, but do not keep it for longer than 1 day. I have seen funk grow in it if kept longer than that. Lucy got her water in a 20 oz travel mug 2x a day.
After her first day of not eating, she only wanted cooked, mashed peas for 2 weeks. She refused anything else, so keep tempting your duck with things she loves to eat. You may have to use a syringe and squirt some liquified food into her bill to get her to eat. which means you will have to take some food and puree it in the blender and add enough water to make it liquidy. Lucy's bill was very sore and I had to mash her peas so she could eat them.
Examine your duck carefully to locate all the wounds you can find. Trim away feathers from the wounds so you can treat them effectively. Don't be afraid to trim away all her feathers if you think you need to to examine her. You can dress her in newborn t-shirts until her feathers grow back. If you keep her in a dim, quiet room, she will heal faster, and eventually start to molt. At least, that's what Lucy did.
Use saline to rinse out the wounds every day. Use a q-tip to pack the open wounds with antibiotic ointment.
If there is a puncture wound (which includes bites), you will need to debride it daily with a gauze pad. That means put peroxide on a gauze pad and scrub the scab off the puncture wound and scrub it enough to keep it open so it can drain. Punctures must heal from the inside out, or they get infected. Pack the punctures with antibiotic ointment, too.
Since you can't wrap a head wound on a duck, just let her wash her head at will. The only wound I wrapped on Lucy was her leg wound while it had Ichthammol on it to pull out the infection.
Let her rest and check on her every few hours. Change her towels at least 2x a day, or get those incontinence pads you put in a patient's bed and put one of those on top of the towel. Easy cleanup and less laundry. I got mine at Wal Mart.
I did not have the money for a vet visit, but if you do, I highly suggest taking her in.