This may be a dumb question (really, read on), but that won't stop me.

I'm hunting for the cause of a sight miss and hesitation on my '90 740 turbo wagon (152k).

My local mechanic gave it a tune up and cleaned the throttle housing. He cleaned the idle control valve, but said it may need to be replaced anyway (he said to drive it for a while and see how it performs). Plugs/wires/cap /timing belt are new.

Being in the mood to work on the car this weekend, I'm going to replace the idle control valve and the knock sensor, seeing as they're bound to go bad at some point anyway. I'm going to clean the flame trap as well.

While under the hood, it makes sense to me to replace any vacuum lines that look questionable. I figure they're cheap, why not?

My questions:

Can I simply go to Auto Zone and buy lengths of vacuum hose?
Do different hoses on the Volvo require different types of hose?
Are there quality issues to consider? (I warned you this migt be dumb). I don't want to remove old but good quality hoses for new but crappy hoses.
Any specific hoses on the car that I should consider with greater attention?
Should I replace everything in sight?

Thanks for any help.