Well it sounds like your battery needs to be replaced, you're overheating problem do you actually know what your temps are getting up too? Hwinfo64 might show you exactly what your temps actually are and how fast your fan is turning. One thing you can try is since your changing out the battery you should clean your Fan and heat sinks they may be clogged up with dust. Blow them out with canned air.

You can try to repair your Windows with a Repair install this may fix your Sleep issues, you should also update any hardware driver that is out of date that also may help with your sleep issues. The issue is programs that are still running when you put it to sleep.

To get this information you need to log on to  Dell Support, enter your model number, and most importantly Enter your Service Tag Number. 

That will open all the hardware information on your Particular notebook, You should download and read your Service Manual there you will find out how to open your notebook

you might be able to get a new battery from Parts People

I have tried using windows repair to fix the sleep issue and it did not work. I have tried various things to fix the sleep issue, but nothing has worked for me. 

Also, should I be replacing the battery or the fan? From my understanding, the fan is making the loud noise and causing the laptop to overheat. Am I assuming correctly?

4. The battery lasts for an hour on video calls and about 2 hours normally. Is there any way to extend the battery life? 

I didn't say a windows repair, I said windows upgrade repair install

I have the same issues with the fan and sleep functions.

Fan is constantly spinning at high speed, even with no app or software is running. (checked through end task manager) Fan spinning so fast that created static noise when i do video call.

All my drivers and firmware are up to date.

Any help would be appreciated. Thanks!