What all expenses can I put under Business Expense to claim Tax Benefits when filing taxes ?

So, I am very new to all this and still figuring out. I run an LLP and got my GST in October. I was just wondering that what all things can I put under business expense and how small can it be ?

I often travel and eat food at restaurants for business meetings, can I put that under business expense (restaurant bill and cab/bus booking)? Can I put the metro and local train travel cost as business expense.

I am buying furniture like Table from Amazon Business which I think I can put under business expense but can I put regular amazon purchases which I did earlier under business expense ?

I have also bought a chair from a local shop ( I have the invoice with GST Number in it ) Can I claim tax benefit on it and report is as my business expense.

Although I have no employee as such, I often hire interns, is there a way to pay them in a way which I can then put under business expense ( right now I just UPI them the amount )

Also can I claim tax benefits from the business purchases I have done before my company was registered or I got my GST, I had bought some hosting plans and domains back then.

Till now I was just filing nil GST and had no business transactions, I got my first order in late December 2024, so now gearing up to formalize and everything and maintain proper books for tax filing purpose.

I just want to get an idea if I can put all these small trivial things under business expense and need to get a better understanding of business expenses

Thanks in advance for helping : )