At the beginning of every school year, I send a very polite email to my kids' teachers introducing myself and our situation. Something like this:
Son is very excited to be in your class this year and we are looking forward to the school year. As you may or may not know, Son splits his time between his two parent's homes. We each have a desire to stay engaged and involved in the goings on at school, but sometimes paperwork gets lost in the shuffle between houses. Would it be possible to get duplicate copies of school-to-home communication? We understand this won't always be possible, but appreciate any accommodations you could make for us.
It has always worked out well. I also read a suggestion here from someone who dropped off a stack of self addressed, stamped envelopes to the front desk to get the mailings. Haven't had to do that, but it's a great idea! And yeah, pictures, usually you just need the code from the packet and you can order online.