I'd post your questions in the Arboristsite Chainsaw Forum. You'll have alot more people see your post and alot more that are qualified to give you answers.

Good Luck!

Any 61 top cover will fit. Over the years the cover color changed, at one time a white cover indicated a consumer saw, solid orange indicated professional.
Not any bar will fit, each saw has a mount pattern that must be matched. Yours uses the Oregon D009 series bar or equivalent. With Oregon the first two digits indicate bar length, the third is gauge or bar groove width. The fourth and fifth are the bar type, the sixth is the chain size. So 188RNDD009 would be 18" .058 gauge, solid with replaceable 3/8 sprocket tip, and Husky or Jonsered large mount (which also fits new 64cc and up Dolmar).

Here is a link that might be useful: OREGON

I did not mean to imply that no one here could be of help, only that your chances would be better at Arboristsite. Of course canguy knows his stuff. Arboristsite is still a great wealth of info if you are into old saws or saws in general.