Do I have to pay attention to anything other than DDR3?
No, of course not ^^ Not every laptop uses DDR3 RAM. You have to use the right RAM standard. In addition, the RAM is soldered in some notebooks. Nothing can be exchanged or additionally installed.
Must be 204 pin sodimm
DDR3 SO-DIMM is called Notebook-RAM, of course, only fits in notebooks that run with DDR3 SO-DIMMs and then there's the "modification" called DDR3L
The current notebook generation runs with DDR4 SO-DIMM
Logically not. You can read out what you have currently installed on yours with tools such as https://www.cpuid.com/softwares/cpu-z.html. You can then use this as a basis for what you have to buy for a bar (if you plan to upgrade). Before doing this, you should find out whether there's even a possibility, more and more devices (especially the cheap ones from Lenovo and Acer) have at least parts soldered and only one slot.
No.
As the nomenclature suggests, before DDR3 there was DDR2 and before that there was simply SD-DDR RAM, now DDR4 is the standard for PCs.
With a mobile device, SO-DIMMs are usually used, which have fewer pins than the conventional DDR DIMMs. Nowadays the memory is even often soldered and there are no more banks to plug in.
In addition, not every board can work with every DIMM, even if the iteration (e.g. DDR3) and connector (e.g. SO-DIMM) match. A board supplies e.g. The banks with a fixed voltage, DIMMs that require a higher voltage do not run on the board, LP (low power) DIMMs can't run on every board.
So not every DIMM, even if everything else is correct, is compatible with every board, but the compatibility is very high, i.e. Most boards can work with most DIMMs.
