Both the English and the Russian words are borrowed from the same Latin word. You'll often see -ия where English has -ion (e.g. информа́ция 'information'), that's because Latin -io is borrowed as -ion in English and as -ия in Russian.
No, trip is literally a word for a holiday travel. We're going on a trip is equivalent to we are going on a tour. You can say "trip to the shop" to mean the travel to the shop but you can also say "we toured all the supermarkets in the area", these words are commonly used interchangeably. I don't think I ever used the word 'tour' to mean going sightseeing, only in the connotation of a "tour guide" at a museum (person or book) or when reading a travel brochure where they offer guided tours on camels or ones away from your location. Excursion is closer to a trip in meaning so someone messed up bad with translations. Excursion is a short outing, and a trip can be to a museum or a shop while a tour tends to be something specific, longer in time or distance.
"This is a good excursion" is accepted. Does not really sound like something we would say in English too much. https://www.merriam-webster.com/dictionary/excursion gives the primary meaning as an expedition. I always took excursion to mean a a bit of extended journey.
It should sound like EKSkursiya (emphasis is only there to demonstrate pronunciation of the first syllable; actual syllabic stress is eks-KUR-si-ya). The intonation on the khoroshaya is weird which is trippin' things up in the third word... Also in reality if you were just speaking casually you probably would just gloss over the "-ya" in khoroshaya anyway.
When "tour" is the subject of the sentence, in English it doesn't really make a difference. "This tour is good" and "this is a good tour" essentially mean the same thing (though I could see the second one serving as sort of emphasis on "good", meaning... it's even better than good, or it surpassed the person's expectations. That would only be detectable when spoken with certain intonation though, written and without context they're basically the same.).
HOWEVER, in Russian, it would be different grammatically - Эта эксурсия хорошая - THIS TOUR is good; это хорошая эксурсия - THIS is a good tour.
It's the difference between "THIS THING" and "THIS is a thing", if that makes sense.
@MinTakaoka - Это means "this is X" or "it is X", it is a generic word that doesn't decline.
"Эта хорошая экскурсия" means "This good tour", which requires more expansion to be a complete sentence ("This good tour costs too much" - "Эта хорошая экскурсия стоит слишком много", for instance).