You can have as many surveys as you want running at one time, with no response limit. SurveyGizmo also does a great job of pulling an overall report. It will autopopulate averages and standard deviations for each question, while still letting you download your responses for a deeper dive. The data is never removed from your account, so you can go back and review old surveys as needed.
It’s easy to earn cash for surveys. How much you get paid completely depends on how many paid surveys you attempt and complete. Each online survey has a different payout, with some offering as much as $50. Most will pay less, but also take less time. Expect to earn about 40 to 200 SB points per survey (100 SB = $1), with occasional opportunities with much higher earning potential.