T43 laptop, my first laptop

1. - Those are really good temps for laptop CPUs. Many in gaming laptops the CPU temp can hit high 80's or low 90's.

2. - As long as temperatures are not very high you should not have any problems. for about the last 9 months I have been using my 15.6" Dell Latitude 3540 a lot. During the week days I probably use it play games for 4 or 5 hours when I have the time. During the weekend if I decide I just want to lay low, I might play games for up to 8 hours. I have from time to time converted video for extended sessions; I would queue up videos to be encoded and just leave the laptop alone. The longest session of straight encoding at 100% CPU usage was around 38 hours. The temps never went higher than around 74C. Your mileage may vary.

3. - Remove the battery from the laptop when plugged into the AC outlet. Many new laptops prevents the battery from being charged past 80% (could be as low as 50%), to extend battery life. The battery can be charged to 100% if you override the power settings (could be slightly different from laptop to laptop because manufacturers use their own custom software to limit charging). Generally speaking, evidence has shown that the longer a lithium ion battery is close to the maximum charge the more likely something called "lithium ion plating" will occur. Basically, the high charge causes a chemical reaction which forces lithium ions to clump together and form "plates", then this happens the lithium ions can no longer retain any charge and the battery life is shortened.

Since the battery is easily removable in many laptops. I recommend just removing the battery.

3.5. - That is normal. For example, it is easier to smell food when it is hot compared to when it is cold or room temperature.

4. - As stated above you can go to Lenovo's website. Typically the only components that are measured for temp are the CPU, discrete GPU, and hard drives. I use a program called Speccy to get stats including the temp of my Radeon HD 8850m. Temps for integrated GPUs like the Intel HD 4000 are not displayed because it is part of the overall temp of the CPU.

https://www.piriform.com/speccy

5. - Try not to inhale too much of the laptop's hot air. You are basically breathing in industrial chemical molecules that are being released due to high temperature. Similar to how hot food gives off an aroma. Generally speaking any amount of heat will cause electronics to release emit odor. It is usually not a big health concern since it is relatively small and it gets dispersed in the air very easily.

The ThinkPad T430 does not have many vents on the underside of the laptop, however, if you are concerned with internal temps you can always purchase a cooling pad to provide slightly better air circulation compared to simply putting the laptop flat on the table. Most cooling pads have fans that pulls air from the underside of the laptop. More effective and expensive cooling pads blows air up the underside of the laptop and into the vents depending on the location of the vents and the size / location(s) of the cooling pad's fan(s).

Assuming you live in the US, Black Friday is not very far way so you might want to consider replacing your old T43 with something newer if you have the funds for it. Assuming that replacing the thermal paste does not resolve your issue.

The Radeon X300 is rather weak in comparison to today's integrated graphic cores. There are a lot of laptops that uses some version of the Haswell Core i3 / i5 "U" model CPUs that has the integrated Intel HD 4400 which can more or less run rings around the Radeon X300. The "U" refers to ultra low voltage CPUs. I would guess you should be able to purchase a budget laptop using a Core i5-4210u CPU for about $350 - $400 during Black Friday. These laptops generally have a $500 starting price.