are these things that can be replaced by someone who is willing to take the time to do it right? or are these very advanced replacements?

I would choose the person who is willing to take the time to do it right providing they know what they are doing, also when replacing the timing belt it is highly recommended to change the water pump, auto tensioner, coolant and power steering fluid the same time.
Goodluck.

I would choose the person who is willing to take the time to do it right providing they know what they are doing, also when replacing the timing belt it is highly recommended to change the water pump, auto tensioner, coolant and power steering fluid the same time.
Goodluck.

is a cat converter something that can be replaced without fancy tools?