Two investment-related questions

Hello, I'm an expat living and working in Korea and I have two investment-related questions:

1. Does anyone have recommendations for buying ETFs based on KOSPI? I would prefer an online platform, with which I can buy and sell ETF shares as I wish. English interface would be a huge plus.
2. My pension is managed by Samsung Securities, and at the moment I have the basic investment option. Does anyone have recommendations on how to put the money at good use? I'm in my 40s, aiming for long-term growth.