You should have about six months of expenses in a safe, accessible savings vehicle. Then, you can put money away in a brokerage account. When you open the brokerage account, be sure to diversify your portfolio.

Nope, savings separate as emergency fund always. Brokerage account separate after that.

Goodness NO. My short-term money is in my (bank) savings account. My long term money (for retirement) is in my 401k & IRA. My intermediate term money is in my brokerage account.

I would say 75% of my money is in my retirement accounts.