13) Hardware Abstraction Layer Version = "10.0.19041.1806"
14) Installed Physical Memory (RAM) 4.00 GB
15) Total Virtual Memory 7.62 GB
16) Device Encryption Support Reasons for failed automatic device encryption: TPM is not usable, PCR7 binding is not supported, Hardware Security Test Interface failed and device is not Modern Standby, Un-allowed DMA capable bus/device(s) detected, TPM is not usable
Yes, you may use 8 GB RAM total. (In fact, more may be possible, but not necessary.) You may use DDR3-1333 SODIMM, DDR3-1600 SODIMM, DDR3L-1333 SODIMM, or DDR3L-1600 SODIMM Crucial has DDR3L-1600 SODIMM available.
For SSD, you may use any 7mm (with a spacer/adapter, included by Crucial) or 9.5mm SATA SSD. An SSD will make your laptop much faster and more responsive, a noticeable difference. Crucial's MX500 SSDs have recently been reduced in price. They are good performance and good value for the price. You could get a 500 GB for less than USD $50 or a 1 TB for less than USD $80.
You don't necessarily need to buy RAM from a big brand such as Crucial. I recently upgraded my 2nd-gen i7 laptop with Kuesuny RAM, bought from their Amazon store. They use well-known memory chips such as Micron and Samsung. They have lifetime warranty and their support is responsive to emails. I tested mine by running memtest86 for several days. I'm happy with the RAM and it was cheaper than Crucial. Whatever you buy, buy a "kit", which is a matched pair of identical RAM sticks. That will make success more likely.
As your laptop is ten years old, then the thermal compound has dried out and is cannot adequately transfer heat away from the processor, and there may be a lot of dust inside the laptop and maybe inside the fan and heat fins. So, your laptop is unable to adequately cool itself.
You might consider an internal cleaning. Open it up to clean out dust. Disassemble the fan to clean out dust and fluff. I found a fair bit in two laptops I worked on recently. Remove the heat sink, remove the old thermal compound and apply new thermal compound before reinstalling the heat sink.
While you're in there, replace the CMOS battery. If it isn't dead, it soon will be. BIOS settings and date/time can't be saved without a functioning CMOS battery.
Whenever touching components or working inside a computer, wear a grounded wrist strap, also called anti-static wrist strap, ESD wrist strap, or ground bracelet. I know many people do such work without this, but it's a cheap and sensible precaution. Rest the laptop on an anti-static mat or at least a reasonable alternative such as corrugated cardboard.
The other user already mentioned, that you can get yourself a nice second RAM , matching with your actual one, from crucial. As long as you go with the same specs, these will be working together. If you can spare some extra cash - Get yourself 2 RAM units with the same specs and manufacturer.