I've never in my life changed the fluid in a manual tranny.  I'm talking
cars with 150k to 200k on them with no problem.  Coolant flush is not a bad
thing, but you can have it done much cheaper, or even do it yourself.  At
five years, it may even be a good thing to change hoses if they are at all
questionable.  They do go bad over time but 5 to 7 years is generally OK.

Can't say for the injector service.  Find out what the real problem is
though.  There are many reasons it can be hesitating.

IMO, the only time you go to a dealer for service is if it is a warranty
thing, or some very specialized problem not easily accessed by the local
mechanic.  Routine tune-ups and preventative maintenance can be done much
cheaper at a reliable local garage.

Your dealer is interesting in putting his kids through college or remodeling
the kitchen more than your well being.  Keep hold of your wallet.

I own a 01 Elantra (manual transmission) - 80k miles.   My dealer
continues to push me to do a transmission flush ($150), coolant flush
($120), and fuel injector service ($110).  I think I need the fuel
injector service since the engine acts like it's not getting gas like
it should.  How about the other services?  Necessary?  I've heard
conflicting advice on the transmission flush... haven't heard much at
all about coolant flush.  Okay price?  Thank you... I wish I could find
a local guy I trusted with this.