Gst tds and ITC claim w.r.t. subcontractor and govt. contractor

I work for the government as a government-contractor - railway bridge & platform repair construction works (HSN 9954) and raise invoice for 12% and railway deducts gst-tds as well as ITR-TDS 

1st question :- 

if my subcontractor is GST-Registered, 
what will be the gst percentage applicable in the invoice he raise (to me) as my sub-contractor - 18% or 12% ? (HSN 9954) 

2nd question :- 

i know that 1% ITR-TDS will be deducted (u/s 194C) [kindly let me know if iam wrong] 
now; 
does GST-TDS also applies ? if yes what percentage ? 
 

3rd question :- 

can i take ITC of the gst amount mentioned in the invoice raised by my subcontractor ?