I suggest what I wear. A full face or modular helmet, a riding jacket, and over ankle leather boots. If you're not comfortable with that, increase it to whatever you feel most comfortable with. You could do the rides in full race leathers with back protectors, racing boots, and an airbag vest, but it's going to be a miserable 1600 km in my opinion. You could do it in tennis shoes, a t-shirt, and sunglasses which would be comfortable, but too risky in my opinion. At an absolute minimum, wear what's legally required in your state/province/country/city/whatever. I see you're in India, so be careful. I've heard that traffic can be very dangerous in some parts of India.
One thing that I've found helps me is a wet microfiber cloth in a ziplock bag. That way, I can clean off that big bug that smeared across my visor with a quick 2 minute stop on the side of the road. I like being able to see well.
The best tip for long distance riding I can offer is very simple. Stay on the bike! 1600km in 24 hours is easy. You've got plenty of time for fuel stops and three sit down meals. The hard part is just staying on the bike until you're finished. You can easily be tempted to get off the bike and take a 15 minute break. Those breaks can get more frequent until you miss the timer. Just stay on the bike and take a nice long break when you're finished.
To offer more tips, can you tell us a bit about yourself? Tips for a young kid on an R1 won't be the same as tips for a grandpa on a Goldwing.