"**is rooting safe**" 
The answer is difficult. Every tool you use to root says **do with your own rish and we are not responsible for any damages caused to your device**.

**is root legal** 

Nothing to do with legal but it voids your device's **waranty**.


**does my device becomes slower**
No , many tools and tweaks are available to speedup rooted devices .


**what is the best tooting tool** 
That depends on what device you use.

**about data loss** 
No data will be lost. However a backup is taken to avoid data loss.

Try googling to fing the best rooting tool for your particular device . 
Or 
You can download some rooted stock  roms (specific for your device) and flash them using recovery.

Try. 
**Kingo root **

This is the best for me.