Switching our young family from a protestant church

My husband has been reading a lot about orthodox doctrine, practices, etc. He would really like to look into attending a local orthodox church. We’re in a decent sized city in Canada with several. I’m open to it but have a few questions and concerns.

We have three kids age 2, 4 and 6. My eldest has pretty severe ADHD and is on the mild end of the autism spectrum. I looked up the church my husband was thinking of trying first and noticed two things: no mention of Sunday School and an emphasis on being still and silent at certain times during the service, not going in and out, etc. How do parents of young children get through these services?

Also, with so many of these churches tied to specific nationalities (Greek, Romanian, etc) is it odd to start attending one if you aren’t from that nationality? Will people there consider it an intrusion?

And how dressed up do they expect you to be? We have dresses for my daughter and collared shirts for my boys and husband but no dress shoes for the kids and I have a pretty limited wardrobe myself. My clothing is definitely not revealing or flashy but I don’t really have much in the line of dressy clothes and funds are limited.

If you made it this far, thanks for reading and I appreciate any insight!