buckworks - 10:06 pm on Mar 4, 2013 (gmt 0)
few hundreds orders a month, not week
That's still pretty good.
Re investment: if you're doing things right, ads you run will pay for themselves with increased sales. You'd have to manage the cash flow along the way but in the end you should come out ahead.
When you say "more staff", what scale of campaigns are you envisioning?