How to find neighbor kids that they can play with?

Good luck!

I had the hair issue, their hair was always kept very short. I had to learn to French braid and do pony tails with a lot of clips to keep the side strands up. (youtube helped me a lot with this) Tell the younger one the detangler is awesome and will help you do her hair better. I also let them play dress up with some of my stuff which helped them get into being "girly"

Also, before doing their hair up I would have "spa parties" we would do nails, facials and light colored lip glosses or flavored chapsticks. I would tell them the finishing touch was their hair. If they still didn't want their hair done, I would do the hair in the middle of the "party" as they were already excited about everything else.

As far as finding kids their age, take them to a local park to see if they make any friends there? You may even meet someone in a similar situation that you can connect with (=

With the 8yr old and eating habits. Talk to your DH and get on the same page as to punishments for not eating and what is acceptable to not eat.

My Skids were the same way years ago. I finally had enough of throwing out food it's way to expensive.

My house rules
They have to eat everything on their plates. Each kid got to pick one exception SS picked mushrooms and SD picked rice (but she eats it now. Guess she grew to like it)
They don't have to eat those foods. If you know SD HATES a certain food you can use that exception. We only let them choose one or SD would never eat another vegetable for the rest of her life.

If they want seconds, we go by the "take all you want eat all you take". If they take it, they have to eat ALL of it. SS is a hog and will put all the leftovers on his plate and then decide his is full. He only did that twice.

If they don't eat all their dinner or they give too much of a fight, no desert. And no anything else. Next food they get is at breakfast.

If they fight too much, dinner goes in trash and Skids goes to bed for the rest of the night. No exceptions. If we are eating dinner at 4:30, too bad. Your in bed until the next day.

I got really sick of spending hr(s) cooking and spending more than my mortgage a month on food only to have it tossed out.

You guys need to set rules. And don't be afraid that she's gonna starve. No one ever starved from missing one meal. She will either learn to eat dinner with the rest of the family or she will face the consequences.

How to style whispy toddler hair and short hair?
My DD2's hair is impossible. Mostly I just comb it and put an elastic in to keep it out of her eyes. You can spray detangler on the brush instead of her hair if it's the "spraying" that bugs her, or you can just use a wet brush (plain water) if it's the actual detangler she doesn't like. (Although I should say, for the toddler I'd use a comb. Start from the bottom, comb just like the bottom inch first, then go around and do another inch up. It's a lot easier to get tangles that way. Keep your hand on her head to lessen pressure from pulling her hair.)

Picky eating.
I'd let this one go, honestly. If she's snacking on fruit (or veggies) then don't worry about how much dinner she eats. Our pediatrician said to look at what they eat over the course of a week - but any particular meal isn't important. Now, if she's snacking on chips or sweets and skipping dinner, then I'd say stop having those things in the house (or hide them). Don't make special meals - that way lies madness! The rule in our house is, "This is what we're having for dinner. You must try ONE bite. If you don't like it, you may have cereal or be excused from the table." (You could substitute something else for the cereal - I like it because it's fast, fortified, they like it, and eventually they can get it themselves!)

How to find neighborhood kids?
Go for some bike rides around the neighborhood! My BS6 has been HUGE into bike riding recently and we've met several kids that way! I like the park idea as well, as you tend to meet the parents too. The library can be good as well, they often have particular events (like "story time" for the littles) that are fun and have lots of kids. In essence, go do some kid things and you'll meet other kids.

You didn't ask this, but I'm going to throw it out anyway. The other big "tip" I'd give you is to let Dad take the lead on a lot of this stuff. It's GREAT that you're involved, and that you're trying to help. But too often men seem to get compliant about your "help" and it becomes an "obligation" instead - leading to resentment all around, both yours AND the kids who have a right to have their Dad involved and engaged with them. Make suggestions to DH about what HE can do with the kids, but make sure that HE is the one doing the actual parenting.

Oh the picky eating. That can be tough. As long as she's snacking on healthy things, I wouldn't care as much. I know from personal experience (and not from any of the kids in our house). I'm a picky eater when it comes to some foods. I'd have her try one bite of everything. One bit and then she can have her healthy snack or nothing, if she isn't hungry. Maybe even look into things everyone will like?

AllySkoo's answer for the hair is perfect.

As for the friends part. Taking them to a nearby park and bikes are definitely a good idea. Sighing the 8 year old up for something is another good idea, if there is something fun in your area.