About BIOS. It seems that newest one is here
, according to this conversation
About RAM, please look here
About CPU, I cannot tell exactly, and you should see about it with someone who can assist you at the repair shop or something, where notebook can be examined at hand. But take a look at this list here
, you should choose CPU that mathes your current FSB, Voltage, TDP.
I only upgraded my HP notebook CPU once, and after upgrade to more powerfull CPU I needed to set lower voltage for CPU by RMClock
, so that the fan would not be at its maximal speed all the time, after the upgrade.