Does forkjoin return results in a particular order?

Yes it returns the results in the same order that you make requests in an array

example,

const bothrequests= Observable.combineLatest(
  this.http.get('https://testdb1.com/.json').map((res: Response) => res.json()),
  this.http.get('https://testdb2.com/.json').map((res: Response) => res.json())
)
bothrequests.subscribe(latestValues => {

});