1. For Development Economics you can refer to Debraj Ray or Thirlwall and for Indian Economy you can pick any of the texts which include Uma Kapila, Mishra Puri or Das Sundaram. For International Trade you can go for Krugman or Caves and Jones.
2. I dont think calculators are allowed in the examination.
3. Regarding cutoffs last year for SSS it was 67.5 and for SIS it was 91.5. Both are for general category students.
"I don't ride side-saddle. I'm as straight as a submarine"