if you buy a new switch it’ll almost certainly come with a wiring diagram showing the different configurations it can be used in.
Two way switching will require a forth core, which could be any colour in your house (however to comply with current regs it should be brown)
You do need a multi-meter or similar to make sure everything is dead – don’t think that just because you’ve isolated the kitchen lights at the consumer unit then it all must be dead – older houses (and some new ones!) have wires going everywhere.
Only way to be absolutly sure is turn the main switch off.
Tread carefully with DIY forums, in my experience they are full of self righteous tin-pot electricians/other tradesmen who’ll tell you that you’ll die if you change a plug fuse, and its illegal to open the door on your meter cupboard.
Household electrics are not complicated, however if legality does concern you make sure you are on the right side of the part P building regs (you should be OK changing switches over)
Just take your time, think safety first and be methodical.
There are numerous books and how/to guides available.
One last bit of advice – if you are not confident you know what you are doing – get someone in.