1) I want to use leverage which I know is dangerous, but is x5 profitable? is it good balance of risk and reward probability? I am also considering x10, or is it too much?
I use 10x very rarely.....it's really only for those "perfect setup" situations. 3-5x is my sweet spot. It gives you some cushion for wider stops.
2) What are good indicators for daytrading in 5 min charts?
ConnorsRSI is great for low time frame scalping. Combined with Bollinger Bands and either RSI or Chande Momentum, you'll have a good scalping arsenal.
3) Is it possible to compound the gains? I know traders have minus days and they just try to go in plus at average of week/month, but is it realistic to compound it monthly or so? And raise your trading budget with it?
Yes but the psychology of trading a larger account and short/mid term downswings in profitability (variance) will slow you down.