Hello,                                                                                             first  of all get the cleaning done.  Opg is required to see the status of your teeth and to make a  exact treatment plan that how many teeth of yours require RCT followed by cap.

Firstly you need to quit tobacco completely or else caps will also be damaged. If the stains are extrinsic then ultrasonic scaling will do all the work for you. If stains are intrinsic then cap is required. You want cap to make your teeth look good so you have to make zirconia or e max caps which are quite expensive (8000-15000) per tooth. Cheaper caps will not give you the desired results. Opg is required for complete analysis of teeth and bone structure. Whichever teeth are weak or sensitive may require RCT also. So yes if you want good quality durable treatment then it will definitely be expensive.

Just a full mouth xray to evaluate your teeth situation. And then crowns. This will cost you around 2000-5000 per tooth.

Hello, You need scaling first for yellowish discoloration of teeth... Yes caps/ crowns are possible... depending on clinical/radiological evaluation if  attrition or erosion is deep you may require Root canal treatment as well. The cost of the  each crown ranges from  Rs 5000 to  Rs 20 ,000 depending upon the material and brand  you choose.