UK Visitor Visa - Financial proof with savings and investments and worth submitting a cover letter?

Hi all,

I went through almost all the visitor visa posts here and still have few open questions to get advice on. Please find my context and questions below,

Context: I am a non-EU citizen who lived in the US for the last 16 years and now on 10 month temporary residency in an EU country for studies. I stopped working late last year and live off of my savings and investments. I am applying for UK Visitor Visa from this EU country. I also have 10 year Canadian tourist visa and my US visa is still valid for another 2 years.

Questions:

1. For proof of living in the country, I am submitting both the Visa page and Temporary residency permit card. Do I need to submit anything else?

2. For financial proof, I am submitting my W2 Tax statement for last year, latest + last 6 months bank statements and some of my latest brokerage statements. Issue is, I don't get any regular deposits into my bank account as all dividends get reinvested. I live off the amount in my savings account (which more than covers my yearly expense). In this case, do you suggest including any other proofs?

3. Finally, is it worth submitting a cover letter explaining my transition from employee to student and how/why this UK visitor visa request?

Thank you in advance!