GST basics for a freelancer

Hello everyone,

I've recently transitioned into freelancing in IT (software development & support) after a decade in a salaried role. I've learned that I may need to register for GST and apply for an LUT. Could anyone guide me on the key steps I should take? I currently have one US-based client, though more may follow later. Based on my projections, I’m likely to cross an annual turnover of 25 lakhs, though this may vary.

Here are some questions I have:

1. Is GST registration mandatory for me?
2. Is an LUT required, and if so, what is its validity? How many invoices can I issue under a single LUT? (I've heard from an auditor that a separate LUT might be needed for each invoice.)
3. Should the LUT number be mentioned on every invoice?
4. Can I claim a refund on items purchased for my freelancing work, such as a laptop or monitor? If so, is there a timeframe for eligible purchases, and could items bought two months ago qualify?
5. What are the timelines for GST filing, and any advice on staying organized for it?

I appreciate any insights you can share!