Questions: 1:Build Scanner 2: Paper vs Live API key

Hello

I spent Saturday reading about market data companies. I read about Polygon, Alpaca (and the split between them in March) and a bunch of others. On Saturday I signed up for the paid market data with Alpaca. I am new to the market data API scene. So now my question.

1: I want to build a scanner of the US markets for day trading purposes. I am looking for 1 min data on all stocks (ideally it would be great to filter low volume stocks and such on the server side, but not required). I read about the snapshot with polygon and alpaca. Can I GET the information for all stocks every minute? Only the last minute. What would the response be like? How many symbols to alpaca cover? Is the snapshot the last full minute, or when you actually grab it? SO starting at 930 am I want to pull all stocks every minute until 4pm. Everyday I start over and delete all the data from previous day.

2: I signed up for the paid market data $9 plan. I did not setup a trading account. All I can see in my account is “paper” API keys. It appears to get live API keys I need to setup an account. Are the paper API keys sufficient for what I need? I will not be doing any algo trading, this is purely for scanner/alert purposes.

Thanks!