WKS,
1) Keep the stock tyres as much as you can if you're especially using it within city. You will not only get good average but good handling too. Changing them is not bad, if you have money you may spend it difference of opinion but you may stick to stock you will enjoy it in the longer run.
2) Full body kit is already available in Lahore, it comes with Spoiler, side skirts and bumper extensions.
3) I would suggest to leave them manual, alterations in longer run doesn't work well, this car was originally came as it is in Indonesia without power back door, desi electricians will try to fit Japanese motors and buttons but along with being expensive they work fine in the start, later they all mess up in rain and washing.
4) Suzuki accessories are not economical, I don't know how you said it, if you compare market with Suzuki then Suzuki is hell of expensive. Seat covers, mat, top cover, steering cover etc can easily be get from market of expensive price still worth less then half of what Suzuki is giving. Search the market and then make your decision. But as far as parts are concerned stick to Suzuki as long as warranty is concerned after that market is way better then Suzuki.
JAZAHKALLAH!