1 pointBoth are fine. In fact, a laptop can handle even higher range of voltages just fine, and especially high-end ones like EliteBook series. Yes, this is a known issue for laptops that were spilled on with Coca-Cola or beer :)) Stock+defaults should be always fine, unless you need something fancy. Maybe read what others achieved modding BIOS in that case Got a ~$5 2xUSB3.0 card on AliExpress got very good speeds, but rather fragile build quality.
1 pointHi! You can upgrade your i5 2450M to i7 2630QM just plug and play, without bios modification.
1 pointHi! Ok. Check PM.