The only different between a MAC and a Dell laptop is the Operating System that they run. MACs can have the same hardware issues as a PC, including overheating, etc. And while the issues with the OS are different from Windows, it still has them. They are no better and no worst than a PC.
Rather than replacing the laptop, trying repairing it. Most of the time when a laptop overheats, it is because the vents that allow air flows are dirty. Get a can of compressed air and blow everything out. Keyboard, side and bottom. Anywhere there is any type of vent. Also blow out anywhere there is a fan. Try to clean the fan itself through the vent.
For the space issue, be sure that you have emptied your recycle bin. When you delete files from your computer they are not removed but rather moved to the recycle bin. Until you empty the bin, the space is not freed up. Then run a Disk Defrag to optimize the remaining space and to allow Windows to detect the free space.
Also check the next time you get the out of space error that it says it is out of space on the C:. Most computers have more than one partition (section) on them. They will often have a D: drive that contains a copy of the Windows install files and other utilities for fixing problems with the hard drive. Often there is little space on that drive and if anything else was saved (r tried to save) to that drive, it will cause errors. You can delete everything off the main C: drive and it will not free space on the other drive.
As for the update, usually when they fail like that it is because it is attempted to update something that is not on your computer. Windows has to run on hundreds of different computer configurations, so it has to release updates for all those different configurations. If it runs for more than 10 minutes without completing, then it is safe to shut things down. It is never going to complete because your PC lacks something the patches needs to fix.
Realize that a MAC does NOT run Windows software. Any programs or games that you have will NOT run on your MAC. You will have to replace all of them with MAC versions of the program or the MAC equivalent of the program. Also there are very few games that will run on a MAC. If you are a gamer, avoid the MAC.
MACs can get viruses, do crash, have to be updated, and can be hacked, just like a PC. They get fewer virsus and less often hacked because only about 5% of computers are MACs, so the virus creators and the hackers usually do not target them. But when they do, they are usually more successful because of the mistaken idea that MACs do not get virsus, so too many MAC users never protect their computers.
Finally, realize that the MAC interface is very different from the Windows interface, There is a learning curve to know where to click and what to do to make a MAC work. And there is far less help and support for a MAC as so few people use them.
Having used both, there is not enough advantages to a MAC to offset the price different, A MAC will cost you about double what a Windows computer will.