Is there a place online where you can simulate strategies programmatically?
Your best choice is most likely a service such as Quantopian or QuantConnect. Quantopian provides equity and futures data and allows you to program trading strategies in Python, run risk management analysis and backtests. The latter option, QuantConnect, has support for Python as well as C# and F# in case you're more comfortable in either of those languages. QuantConnect also has higher resolution data for several more asset classes.
I do not use either platforms as I prefer to be using a proprietary setup, plus most of what I do is in C++ and there aren't any online services for that regardless. I will not go into setting up a local environment for developing trading algorithms as you specifically asked for "a place online" and it's a loaded question.
Regarding data resolution: QuantConnect allows you to specify what resolution of data you wish to use in your strategy. Daily, hour, minute and second data is provided by QuantConnect (as well as fundamental data). Same case for Quantopian but there the smallest resolution you will have access to is minute data.
Regarding research frequency: This question is a bit broad but I'll try to cover what you're asking. It depends completely on what you are looking for. There are things you cannot find from daily data that you can find by looking at tick data and vice versa.
As far as old S&P data goes, as stated above both Quantopian and QuantConnect provide data for researching purposes. (The research environments are effectively a Jupyter Notebook, and the language used for that is Python).
This question was a bit broad but I hope I answered what you were looking for.