OLTC to 1,0000 kVA, 11 kV/433V Transformer?

Can you use it for what?

Yes you can use it for on load tap changing transformer windings.

yes you can use only if your application allowed other wise oltc cost is more, you use off load tapchanger, genrally 10 mva transformer are used for power distribution & due to oltc cost people not use OLTC, if the application is critical like arc furnace or other u definately use.