Me and my late hubby’s Micky plush doll (long story) are traveling to DW sept17. Questions-
*Will cast members help you take " flat Stanley" mickey pictures?
*help me understand how soaked I will get on splash mountain and how I take care of my camera and mickey?
Yes, cast members will always take photos, as will most guests if asked! You can never really tell how wet you will get on Splash. Sometimes if timed right you will be completely dry, other times, you need to dry your clothes 
will you have a backpack? Maybe you can wrap them up in your bag? I keep a plastic back with me to protect my electronics. I think you should get your Mickey a “I’m Celebrating” button and enjoy!
Cast and other guests will be happy to take pictures for you.
As was stated you can get soaked to the bone, or stay dry, it is hit or miss. I think if you enter the boat first and slide all the way in you should avoid the worst of the waterfall. It usually is not bad unless you happen to get stuck there, as in boats back up and you may stay under the waterfall. The drop doesn’t usually get you wet, although sometimes the water will slosh over the boat into you and other. Plastic bags are your friends for what you want to stay dry.
Do enjoy your trip and I hope there will be happiness for you. It sounds as though you will be doing a project for some grandkids perhaps.
Regular white gloves try a costume shop, a dress shop, think bridal. But party store/costume shop will be the cheapest.
Large 1gallon ziploc bags are your friends! Just toss Mickey and gadgets inside and close. I’ve never gitten more than a few drops and maybe wet butt syndrome on splash. Beware KRR though, that one was squeeze your unmentionables out in the bathroom kind of wet. Have a great time @nanbhack1!
Btw what is the pin " I’m celebrating" about? Is that like - your first time at WDW? I understand I am getting one of those too.
Yes, it is the same as a “first time” pin. It sounds like you should be celebrating!
I’m celebrating is for more vague things like losing a first tooth, anniversaries, etc. you can get several celebrating buttons. But you only get one first time button! Enjoy your trip!