Wider tires generally add to a more comfortable ride and better road holding.
It's really situation dependent. The wider the tire, the more it distributes weight, which means less ground pressure. While this is desirable in sand and mud, it's quite the opposite when driving in rain or on icy roads.
For unimproved terrain, yes. However, certainly not on wet or icy roads.
You cannot rotate tires on a vehicle when the rear tires are wider than the front. They must stay where they are,
Wider road bike tires can be faster than narrower ones because they provide better traction and stability, especially on rough or uneven surfaces. However, the speed advantage may vary depending on the specific conditions and the rider's preferences.
No wide tyres or better because the give more grip Actually wider tires don't give you more grip in snow. They simply allow more snow to pile up in front of the tire. On Ice or snow pack a wider tire will provide better grip but in deep snow the thinner tire works better. Chicago winters taught me that.
My van has bad tires at front and better ones at rear, should wheel alignment be performed with bad tires?
Branded tires normally offer a longer warranty than the unbranded options.
Well, inflating them a bit harder will make them a bit rounder. But if you overdo it the tubes/tires might burst. Most bike tires have their size written on the sidewall somewhere, if yours is a narrower kind you can have wider ones fitted.
ones bigger ones smaller
Yes, you can convert a road bike into a gravel bike by changing the tires to wider, knobbier ones, adding a more comfortable saddle, installing a lower gear ratio, and possibly upgrading the brakes for better off-road performance.
Your local mechanic may have some good ones. Another option for good tires is when there are over supply sales. Meaning you can get a good price on tires and they will be better than used.
The best tires for a small car would be the ones that the car manufacturer recommends you use on the car. If you keep good tires on your car and check them every now and then you will get better gas mileage.