(a) You are being appointed in a Central Government service. It is a fresh appointment, not a transfer. So, you will not get any transfer grant. There is no scope of doubt or confusion about it.
(b) There is no Grade Pay system after implementation of VIIth CPC. The equivalent pay scale of GP 2400/- is level-4 , i.e., Rs. 25500-81100/-. As you are an initial appointee, your pay will be fixed at bottom of level-4. So, your basic pay would be Rs. 25,500/- p.m. Over the basic pay, you will get Dearness Allowance @5% of the Basic Pay. This will increase twice every year, in January and in June. Besides Basic Pay and Dearness Allowance (DA), you will get House Rent Allowance (HRA), the rate of which depends upon the the city where you would be posted. If you get Government accommodation, you will not get HRA. In addition to this, you will also get Transport Allowance, the rate of which again depends upon the class of city where you will be posted, and DA @ 5% on Transport Allowance.
Beware! I question everything and everybody.