What about other safety as battery cutt of etc`?
There is none. That's what makes it a "mechanical" mod instead of a "regulated" mod -- there is no regulation whatsoever, it's just a direct electrical connection from the battery contacts to the atomizer coil. You can buy a fuse that sits in-line between the battery and the atomizer and will blow if the current gets too high, but that's it. The only other safety features on a mechanical mod are your brain, and the vent holes that prevent it from turning into a pipe bomb if thermal runaway occurs and the battery starts venting hot gasses.
You will need to use Ohm's Law (Amps = Volts/Ohms) to keep your amp draw below the battery's recommended specifications. Since there is no voltage regulation on a mech mod,
you need to do all your calculations at 4.2v, as for a fully-charged battery. This means that the only way you have of controlling the current, is by controlling the resistance (ohms) of your coil build. You
will need an ohm reader or multimeter, if you don't have one already.
You must use the battery's "CDR" or ("continuous discharge rating") value, and NOT the "PDR" or ("pulse" or "peak" discharge rating). Since you will, presumably, be firing it for more than a few miliseconds at a time, the PDR spec is useless. Make sure that the coil build keeps the amp draw below the
continuous discharge rating, or else you may get into trouble. It's also probably a good idea to leave yourself a good 20-25% margin of error. This means if your battery is rated at 20A, you'll want to keep it down around 15-16A just to be on the safe side.
At 4.2v and 15A, this means you're looking at:
15 = 4.2/Ohms
15*Ohms = 4.2
Ohms = 4.2/15
= 0.28 (or higher -- remember,
lower ohms means a
higher amp draw and vice versa)
Of course, if your battery has a higher amp rating, then you can safely go to lower ohms, but make sure to keep yourself well within the specs. Also, note
this post about the purple Efest batteries not being up to their advertised specs. The "35A" battery is actually only good up to 20A, and the "20A" battery is really closer to 6.5A.
EDIT:
Also the atomizer itself may be rated for a certain power consumption. Power (in watts) is equal to volts times amps:
Watts = Volts*Amps
Since the amperage is already a function of the voltage over resistance, you will need to calculate that first based on your coil build, and then multiply by 4.2 to get the maximum power output of your setup. At 10W max for your coil, you're now looking at:
10 = 4.2*Amps
4.2*Amps = 10
Amps = 10/4.2
= 2.38
So now we know that the maximum amp draw should be no greater than 2.38, we can plug that back into the first equation:
2.38 = 4.2/Ohms
2.38*Ohms = 4.2
Ohms = 4.2/2.38
= 1.76
So you'll actually want to keep your build above 1.7-1.8ohms. Your
battery (if it's 20A, as in the example) will be able to handle coil builds as low as 0.28, as discussed earlier, but remember that's putting out 15 amps, or 15*4.2=63 watts of power to the coil.
Sony VTC 4's would be the purrfect batt for the op too. 
