When we lived in the UK, my dd had a removable expander (like the old retainers) - it was FABULOUS. She turned it herself, she cleaned it, she could brush normally.
Fast forward to our return to the US, she's about 1/2 way through the expander. We interviewed 5 orth's and NONE would use a removable expander. As one orth said, "you can't trust a 10 yo to advance it". Sorry bud but she was doing just fine when she was 9, sigh.....
She had some pipe cleaner thingies that she used between the wires (wait, that may have been with the braces) - as for the pain, I do think it's absolutely normal as every person is different. Today, 6 years later, my dd still has a smoothie every day - even though she's been out of braces for over a year.
Besides smoothies, she liked grated cheese, yogurt, applesauce.... you get the idea. :)