Yes. The B2B platform is a legitimate website. 
The Alibaba Group owns it. However, individual sellers need to evaluate the trustworthiness of suppliers.

Of course not! They aren’t! 1688.com has more Chinese suppliers. 
Conversely, Alibaba.com focuses on international suppliers.

Yes. But be prepared for language barriers, longer lead times, and complex logistics. 
However, you can employ a sourcing agent. They can ensure your experience is smooth sailing.

The advantages are affordable pricing and product variety. 
There is also the possible customization from suppliers.

1688.com drawbacks are language barriers, quality concerns, and complex shipping.
Also, there are potential intellectual property risks.