Well....as Nixon would say, "Let me say this about that".
I'm a licensed limited energy electrician, and I do network cabling for a living. Our company has several network installers at each of our locations. We work with the line voltage electricians to get the customer the full service deal. Please don't lump everyone into a label and say that an electrician cannot know how to do network wiring. Some do.
The advice is good, find out what the electricians qualifications are and how he will warranty the cable installation. Proximity of data wiring to electrical circuits is important, and if you look behind my installed equipment, you won't see it all crisscrossed, because that is sloppy and troublesome.
If you want to wire for the future, consider following the EIA/TIA standards for residential wiring. Essentially that will get you 2 cat5e's and 2 RG6 coax at every location, home run to an equipment room and terminated properly on a panel.
Here's my two cents worth:
1. Anywhere you think you might want a phone/data/tv/camera etc., put wire to that location or if you are unsure what will go there put conduit to that location.
2. The standard recommends 2 cat5e, 2 RG6, but it really is somewhat impractical for some things. I may want a phone by the toilet when I'm older, chances are i'm not every going to have a need or room for a computer or television set right there at any time. So, I'd just run one Cat5e there for a phone.
3. I'd stick with 5e as a minimum for phone or data, personally I like to use two different colors cause it looks clean and easy to sort out. When choosing the RG6, I would select a product that has a solid copper core. Most cheap stuff has a copper coated steel core which is ok for TV, not so great for video.
4. If this is your home, pick where you want the outlets, and listen to someone who has wired many homes. Designers and Architects (generally) care about how it all 'looks'. They dont have to live there, they dont have to use the stuff, they just want it to look pretty. Think it out, think about where you might want an outlet, you dont have to plug anything into it, but at least put them where you anticipate doing anything that requires connectivity.
You may want to find a custom home outfit, one that does home theater and sound systems and the like. Those folks usually will walk through and give you lots of ideas.
Anyway, good luck! It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com