|What are the best RAM:FSB ratio to get the fastest speed?|
Generally the best ratio is 1:1 although 1:2 is also an option. And that ratio is based on frequency, not the bogus FSB or DDR ratings. In other words, your 533MHz FSB CPU has a frequency on 133MHz, so you need RAM that runs at 133MHz (266MHz DDR) for 1:1 or 266MHz (533MHz DDR) for 1:2. It won't hurt to run DDR2-667 but the ratio will be 133:333 (2:5) which is less that optimal.
"How do I check if the BIOS has the facility to alter RAM Tinings?"
You simply enter the BIOS & look to see if the settings are available. On a laptop, chances are they're not. And even if they are, altering timings doesn't do all that much to improve performance, & if you don't know what you're doing, it can possibly make the system unstable.