Selling a large number of shares at once, insight appreciated.

Hello everyone,

Thank you for taking the time to read my post.

I'm relatively new to the world of stocks and I'm reluctant to invest much money until I understand the process a little bit more. Apologies if the following questions are laughably basic or obvious.

Say I had $10,000 to invest on a single stock (purely hypothetical, I know it's generally bad practice to do that) and the asking price was $10 a share. How would my investment affect the asking price of the stock? Would it still cost $10 for others or would it increase by a certain amount?

In contrast, say I had 10,000 shares in a stock and I wanted to sell all of them, would they all be sold at exactly the same time at the same price? Or are there scenarios where only a certain amount of sells can be fulfilled until other traders buy your remaining shares?

A real-world example, the UK-based cinema Cineworld recently had an ask price of a few pennies. It then shot up to £7. If I bought $50,000 worth of shares before the price rose and then tried to sell them at £7, is it a guarantee that every single one of my shares would be sold at the same time?

Thank you so much for any helpful replies.