Experience certificate is mandatory for an experienced candidate?

I have work experience but no certificate because, I have to pay the bond amount in my company if I want to break the bo

Do Professional LOR’s require any stamp from the company?

Do we need to get the lor sealed / stamped or is it not required and can we submit a pdf?

I'm planning to go US for this spring 2022.I haven't taken any test so far. IELTS slots are filled till November. Looking for GRE waiver universities. I'm planning to take Duolingo test in next 5 days.

with only duolingo score will I make it to US for this spring 2022. If I start applying for colleges from Sept 15 onward

Which University is good to apply with CGPA 6.9 & IELTS 6.0

University of Texas at Dallas or CSULB/CSU Chico