갔다와서?? would be 갔다왔어??? It means you want to check someone go and come back. For instance 1) When a mother wants to know whether her son go to cram school, she can say " 학원 갔다 왔어?" 2) When you ask someone to stop by somewhere such a post office, a bank, a department store you can say 우체국(a post office) 갔다왔어? 은행(a bank) 갔다왔어? 백화점(a department store) 갔다왔어? 완전 is a noun which means that there is no defect. → complete opening of domestic market 너무 means way too I guess... → It is way too salty.