Hello StressBunny,
I agree with all the others. 45 minutes of homework is a HUGE load for any child in Gr. 1, let alone one dealing with Autism Spectrum Disorders (ASD)/ADHD. Too much. If you can have the IEP modified with a no homework stipulation I think that would help all of you.
With regard to learning styles, Marg provides some really good background information, especially about learning how your child learns, and adapting the way you and the school provide information to cater to those learning styles. In fact, it might be worth focusing on learning styles as part of a revision to your difficult child's IEP.
I also agree that The Explosive Child is a great resource.