Here's what I would do:
1. At around 4-5 weeks (I can't remember how old your kittens actually are...they do look quite young, though), begin making a KMR/formula porridge for them...mixing up their regular formula with increasingly large portions of wet kitten food. Once they've taken to this, decrease the amount of formula gradually, until they're eating wet kitten food. Once they've mastered this, you can begin to leave amounts of dry kitten kibble out for them, if you like. By about 6-7 weeks, they should all be eating real kitten food...remember, wet food is better than dry!
2. Take them all in one big hoard to a low-cost spay/neuter clinic and have them done BEFORE they are adopted out, at approximately 8 weeks of age...this way, you are absolutely ensuring that they will not contribute to the problem of over-population. If you adopt them out before they're fixed, there is NO WAY for you to ensure that their new owners will take care of it with 100% certainty.
3. Don't adopt out before they are 10 weeks of age...12 weeks is even better. Although they may be eating solids and litter-trained...there is a period of socialization that needs to happen before kittens are truly ready.
4. For a fee, I would charge no less than $20.00 per kitten. If someone doesn't want to pay this fee, then apparently they're not too terribly concerned with the expenses that follow (food, veterinary care, supplies, etc.) the animal throughout his or her life. There is no such thing as a "free kitten"...all pets have their expenses, from vaccination, food, litter, medical treatment, toys, etc. BE LEARY OF ANYONE LOOKING FOR A FREE KITTEN!!! If you're adopting out animals that are already spayed and neutered, why shouldn't the adoptee pay a fee for the animal? Trust me, in the grand scheme of things, $20.00 for a spayed/neutered/wormed/hand-raised kitten is a GREAT DEAL!
Hope this helps!