680 is strong enough for top 30. 10 years WEs are favored by Wharton, michigan, darden...
usually 6 schools are OK. 2 possible, 2 likely, 2 back up.
The success depends on your essays, interivews, WEs, GMAT, GPA, TOEFL,...
Essays and interviews may be the most important for you.
BTW, if your oral English is not strong enough, don't risk taking the in-person interview with ADOs. ALso , if your essays and materials are not prepared well, don't take risk of submitting early.
The quality is very important.
You'd better carefully identify different information, otherwise, you will make some mistakes and waste time and money...