Are the shares in my demat account safe?

What is the process to dematerialize my physical shares and is it safe to keep shares in DP account? I am worried after the Karvy case.

My sub-broker was suggesting that I leave my shares with the broker instead of transferring into my demat account. Is that fine?

I was having a demat account with a broker who was banned by SEBI a few weeks ago from participating in the markets. I am now worried about my shares in my demat account.

Can I directly apply for IPO shares in my demat account?

Can I participate in securities lending and borrowing mechanism using my shares in the demat account. How will it work?

I have some shares in my name and some in joint names with my wife and some with parents. Can I demat all these shares in a single demat account?

How will I get my dividends and bonus shares in my demat account?

What is the process of pledging my shares in my demat account if I do not want to sell it?

Do I have to have a demat account with a lender to get a loan against securities/shares (LAS) with the same lender?

How do I pay the interest of my loan against security/shares (LAS) accumulating in my account every month?