forgive this post its gonna be all over the place...
in most homes with relitively short runs of Cat5e/ cat 6 then go with which ever is cheaper (cat 6 is coming down in price a lot) however cat 6 is more expensive to terminate and generally more of a PITA than cat 5 due to its less flexible construction.)
Cat 6 theoretically has higher speed capability but in a house with short runs, im not sure youd notice
i ran about 2000' of cat five around my modest house to give you an idea. every bedroom has 2x cat 5 and also a draw wire on the opposite side for future cat 5.
master bed has 2x cat5 to each side of the bed and also 3x cat 5 to everywhere you may want a TV.
Basically you can run the cat5 yourself. its not hard. and remember cat 5 is cheap so go crazy and put it wherever you think you might want a piece of tech in the future
16 gauge is too small for your main front speakers. you need to run 12 gauge to those and preferably in 1" conduit so you can add another run in the future if you need to bi wire.
heres what i ran for my new build from my media cupboard to my lounge..
2x hdmi Thick gauge wire as it was a 36' run
3xRG6 aerial cables
2x screened 4 core for remote blasters etc.
4Xcat5e
1xSPDIF optical lead
2 core power cable for balun/splitter/converter power if needed
also ran..
14 gauge speaker wire for all speakers in room except main fronts which are 12 gauge in conduit.
also ran a conduit to the center position behind the TV for a random yet to known cable in the future.
there are plenty of places to get cheap speaker cable the names of which escape me at the moment...sorry. have a search on avs forums etc
all the "spare cables" not directly plugged into the tv are run down past the TV into hidden connection boxes just above the floor so that if you want to add a media cupboard in the future below the TV the wiring will be long enough, this also allows for the spares to be used as draw wires to pull stuff up from below TV to TV etc. dont forget that spare power cable for 12volt power to power any hdmi baluns etc that may be needed.
make sure you put plenty of timber in your walls for TV brackets!!!!
AND TAKE LOTS OF PHOTOS AND MEASUREMENTS so you know where stuff is once the wall lining goes on.
Im not sure what your house design is or what your code allows but i used lots of blue strapping tape as future draw wires in my walls so if ever i want to add a power point or whatever, ive generally got it covered. the packing tape is dirt cheap and saves $$$$$$ down the line in labour or having to pull off wall linings to add something
HDMI runs have a limited cable length so if your cable run for HDMI is over about 35' the use cable with thicker gauge strands(probably be ok up to 50') or then youll need 2xcat6 or cat5 per hdmi run you need and use baluns at each end.
heres my tv setup:
packing tape draw wires in wall next to media cupboard: