You’re in luck on the first half. I was working in the McDonaldland costume shop about the time they were making the change. This was not the shop that designed the TV costumes, but the shop, in Milwaukee WI that made duplicates of them to rent to the stores.
The original costumes were, Ronald, Mayor McCheese, Officer BigMac, Captain Crook, Grimace, and Hamburglar, with Birdie, coming later. There was also a Professor, with a lightbulb on his hat, but I’m not sure when he was popular I’m not sure of the date for the original designs, but refer to URL: http://www.straightdope.com/columns/990827.html
Designs were changed by some designer in CA for the commercials. Probably because they were too creepy, IMHO. Not appealing to kids anymore. And I’m sure the lawsuit didn’t help.
Designers and advertising execs like to change things. It’s mostly about increasing sales, but I think they also get bored and want to fiddle around. There was a hell of a mess for us about this time when Ronald’s hairdresser changed the style of his wig, “just because she felt like it.” She didn’t check with Corporate. There were emergency meetings, and we were rushed to Chicago to learn the new style and she prepared a video so that thousands of Ronalds could relearn how to style their hair.
I worked in the shop, which was a Godforsaken Hellhole, BTW, from 85’ to '87 approx. They had already done the Captain, so guess that he was changed, '83-84. They dropped him around the time that we got our version of the costumes compleated. Kids don’t eat fish sandwiches, so there was no need for him.
Hamburglar, Grimace and Birdie were all redesigned next. The commercials were out around '86. We had finished Hamburglar for the field, before I left. The old Hamburglar was hideous, with grey stragly hair, adn a long skinny nose. The new one looks like a red-headed kid. Birdie didn’t change much, she switched to satin overalls. Grimace got Goofier. The rest of the characters disappeared about this time. They didn’t represent kid foods, so the weren’t necessary, from the marketing standpoint.