I personally suggest you to buy TS-PC, I am using this and really its too good I bought it last year in June from ReeCoupons and really its working very well, I highly recommend you to buy it well its totally upto you.
You want something realistic? Then the DRS should work in any place of the track, with the penalty that carries if you open it in a no DRS zone. In Real life drivers can open it wherever they want, I've seen a couple of penalties because of that.
You should begin for learning the tracks, so I would recommend to turn off the dynamic trace (I don't know the actual name of that in english, I speak spanish) and learn every braking point as well as the gear you must be in. After that you can go to medium traction and on. Ah, of course you should play with no braking assist from day one. Cheers mate.