1. Dieseltronic is a sure-shot way of getting a bump in power. It costs ~20k I think but is worth every penny. Since you are keeping the car for long, it would be good to get a DT box for your Swift.
2. Which type of DRLs? Cheap ebay.in DRLs are of 2 types - COB strip or LEDs. COB strip sticks on smooth surfaces and won't fit on Swift's bumper (I have tried personally in friend's Swift). LED ones are better as they will fit snugly on the lower airdam of your car. You may need to drill small holes (with screwdriver, very small) to mount the LED DRLs. Fit them on corners of top slat of airdam, it will look good. If you plan to spend 5-6k, get Philips Daytime DRLs which will also fit like the LED ones.
3. IRVM mount display means that you will lose Day/Night functionality and the clip-on mirror will vibrate on bad roads. A dashboard mount is much much better. See the DIY thread of Saroya, he got one for less than 1.5k (total kit).
4. Yes. If you want help, I will let you know the process of changing to white bulbs. I have done DIY in my friend's Swift for this. If takes maximum 10 minutes for the job. LED bulbs are available but they conk off quite soon. In my Swift, I have changed close to 10 sets because of excessive vibrations from my ICE. If you can find, look for Philips Halogen W5W bulbs which are same as stock halogens but have a blue coating, which gives slightly dull but white light.
Hope that helped!