1. What's your original rim size? If u change back the same size rim with same tyre size then is only for cosmetic purpose. Better handling only refer to if you change to a bigger rim with wider tyres. Then for sure grip better.

2. Usually original and non original is material and quality difference. Ori rims are usually much more harder, tougher and lighter compare to those replicas one which are cheaper in price. If 1st hand too expensive u can opt for 2nd Ori rims. Quality still same just that new and old. If you're buying a new car why want change 2nd rims? Unless the rim looks superb new. If not don't match. Worth or not is very subjective. If u buy an Audi for 100k+ what is a whole set of wheels for 5k?

3. Taiwan ok but not Thailand. Thai rims are cheap but quality not good. Kena lubang sure break into half if u use low profile tyres like series 40. Taiwan still ok coz price still fair. I'm using Taiwan TE37 17" for my Vios wt 205/45/17 tyres. So far ok. But try to avoids holes and big bumps la... Obviously Japan and Europe rims are best. Just that the price is high only. At the end it depends what vehicle you're using. If you're driving high performance car u need better wheels of course. With higher price comes better quality and performance.