What brokerage house to use to buy single stocks and ETFs. Also I am a foreigner but been working here for some time ?

You can use any of the brokerages. Some of the more focused and user friendly brokerages would be like OCBC securities and FSM ONE.

Particularly FSM ONE which has easy stock filtering tools and helpers.

You can check out the brokerage fees per transaction and which interface you will ultimately prefer.

I believe Seedly has some reviews which you can find on the site.