W8-ben or w8233

I'm an Indian freelancer, providing translation services, working remotely with Centific Global, a US-based company, from India. I have never been present in the US, nor the US taxpayer, or any connection with the US, except working with a US-based company as a freelancer remotely. I have to submit a TAX form. Based on my circumstances, I am either required to fill up W8-BEN or W8233. If I fill out W8-BEN, then what to fill in Part-ii, claiming tax-treaty benefit? 1) Relevant Article & paragraph: Article 14 or 15 and Paragraph no.? [ At some places, it shows article 14 to be Independent Personal service, While in others, article 15 to be independent Personal service. Which one is correct, or up-to-date? Please provide the latest original reference. 2) Withholding rate to be 0% for me, as per the nature of my income as well as since I have never been to the US, right? 3) Lastly, most important, an Explanation on eligibility for the rate of withholding (*under 200 field length and valid input) Please help me with this.