The question regarding Extended Warranties is pretty basic ... have you been buying them in the past?
My point is you either ALWAYS buy them or you NEVER buy them.
Any other strategy (buying some and not buying others) will cost you more money than either of the first two, because breakdowns or warranty-eligible incidents are random (more or less) so you cannot reliably predict which thing you buy is going to break, or when.
If you always buy them then you get the protection they offer at a certain price premium.
If you never buy them then you eat the cost of repairs out of your pocket.
It's a one-time decision, however. You will probably be money ahead by never buying extended warranties, but in order for this to work you need the ability to pay for a possibly costly repair every so often. That means you have some savings mechanism in place so that the money is available to make the repair immediately when required.
If you are not the type to have some resources available to you (for example, you pay for repairs with a credit card instead of own resources) then you should consider buying the extended warranties, because your lack of savings discipline means you cannot have an unforeseen repair taken care of immediately. You are, in essence, pre-paying the repair bill, which you may find to be a strategy that for you is easier to manage.
