I need to know that is there any Apple account/id creation limit through iTunes from a computer?
There is no limit of Apple ID creating attempts through iTunes on the MAC computer. I personally helped more than 80 people to create a new Apple ID without credit card. No problem! There is a limit of 3 attempts for Apple ID activation on any Apple gadget (iPhone, iPad, iPod or MAC). Activation process occur when you enter new Apple ID account info into Settings > iCloud for the first time. This limit can not be reset... Even if you ask Apple support team, they will refuse to do that.
Not that I know of. And if there is, you can always switch between multiple iTunes libraries you create on the same PC via the SHIFT + Start feature.
How many are you looking at creating?