I'll list the alternatives and how they compare:
R9 280: Features 3GB of VRAM which makes it more capable of handling higher VRAM usage than the GTX 960 2GB models. Generally on par with the GTX 960, but the 960 is a newer design that can benefit more from the latest driver updates and optimizations. Not as quiet or cool-running as some GTX 960 models, but it
currently goes for $150~160 at the lowest, which is a very competitive price.
R9 280X: Next step up from the R9 280. Same flaws and advantages (3GB VRAM and older design), just at a higher performing level. Offers more raw performance than the GTX 960, but IIRC in some games the GTX 960 is capable of matching or even slightly exceeding the 280X.
Currently available for $215 at the lowest which isn't a great deal, I usually only recommend them when they drop to around $190 or better on sale.
R9 290:
If you can spare the extra $30+ to get an R9 290, it's a pretty good deal.
It offers performance just under that of the GTX 970 and therefore is quite a bit more powerful than the GTX 960. 4GB of VRAM makes this a solid choice for 1080p gaming at higher settings for the next few years.
The GTX 960's main weakness is being limited to 2GB of VRAM. There are 4GB models of the GTX 960,
but they cost very close to the R9 290 which also has 4GB VRAM but is more powerful, making the GTX 960 a worse buy in terms of performance. The GTX 960's main advantage is lower power consumption, less heat, and some models offer zero fan noise at low temperatures.
All of these graphics cards will run just fine on a 600 watt power supply. Depending on the games you play and what level of performance you want, it might come down to how well the cards perform in games that you enjoy or are anticipating to play. For example, if you were wanting to play the Witcher 3 at 60FPS, then I'd recommend the R9 290 which is capable of sustaining 60FPS at medium settings, according to
Techspot. If you're OK with 30FPS or lower settings, then the GTX 960 would stand out more because it can do that and offer lower temperatures and noise.
You are not required to update the BIOS, but you can if you like. Updating the BIOS from the option in the BIOS menu is preferred over Windows-based BIOS updaters. You never know if something in Windows may interfere with the BIOS updating and if it stops midway through, you're screwed.
Looking at the update changelogs, it seems that MSI is adding quite a bit in terms of functionality and compatibility, so go ahead with the BIOS update if you like.
Installing RAM is very straight-forward. Check your motherboard manual for the correct slots to fill up first. It's usually staggered and kept even on both sides of the motherboard.
As long as you're not expecting to play games, the onboard graphics will definitely be just fine for day-to-day use. Premiere, Photoshop, and After Effects will still work but without the benefits of GPU acceleration, so some tasks might take longer, that's all.
