The pants/jeans issue is a Sensory issue--my daughter has mild Sensory Processing Disorder, and the issue of pants/jeans and the feeling of clothes (scratchy, itchy, too tight, uncomfortable) is a very real issue with her. (I had it myself as a child, though not to the extent my daughter does.)
I make her try on all her clothes before we buy anything, and if she even acts a little uncomfortable or says anything negative about the clothes, we don't buy them, because I know she'll never wear them. She doesn't like anything that zips or buttons or snaps on pants==likes only pull-ons/elastic waist. She is tall and large/big-boned for her age and already wears Misses sizes, so I've been buying her pull-on denim pants. We can shorten them usually with no problem, and she feels more like the rest of the kids (she's 9 and in the 4th grade).
It is my hope that as she grows and stretches taller and her waist thins out she might try "regular" jeans--or at least the jeans that snap/button and zip that have the elastic side waists. But that's her decision, not mine to make. It's not easy, but a little sleuthing and you should be able to find some clothes manufacturers who make dressy/casual pull-on pants. And yes, it's very possible that her clothes are bothering her enough that she can't concentrate on what she should be concentrating on. If there's a piece of clothing that irritates my daughter, you can bet I hear about it when she gets home!
***EDIT: I wanted to add that, until this year (4th grade), my daughter basically grew up wearing leggings and sweatpants. This year we're adding pull-on denim jeans and other pants that are elastic waist and can be shortened. But she still loves her sweats, and we've also bought her a few dressier athletic pants. I would much rather have her comfortable and happy than have to pitch a fit about clothes. Also, I've noticed there are a lot of boys in her school who wear sweatpants to school, so I don't feel as if I'm the only one letting my kid go to school wearing sweatpants (or other "not dressy enough" clothes). I figure the pressure of other kids as she gets older will necessitate us reexamining the "regular" jeans issue, but we'll cross that bridge when we come to it.***
I can't help with any suggestions on remembering to bring home homework. I can say, however, that having to do homework every night is a struggle in our household. My daughter uses every ounce of attention she has to get through the school day; it's like pulling teeth to get her to have a few more minutes of attention to spare on her homework (she's very intelligent, so it's not for lack of not knowing how to do the work).
Keep up the good job of feeding your family good food and trying to stay away from processed food. I know; it's very, very hard. Sometimes kids with sensory issues have a heavy metal toxicity built up in their systems, which can cause brain fog and forgetfulness. I took my daughter to an Integration Doctor, who tested her and found she was very severe in her heavy metal toxicity levels; she has since chelated four times, and it has made a tremendous difference in her listening, focusing, retention, as well as the moodiness, outbursts, and temper tantrums she'd been having. It's worth a look. You might discover your daughter's body is full of heavy metals and, after getting rid of them, you might have a whole different daughter.
Good luck.