You will need a crimping tool for patch leads etc also, an idc tool is a must for putting the cables in the back of the patch boxes etc.
Yes you can run telephones over cat 5 and you need to know what tlepeohne system you are running through before you purchase the converters. Although you can just plum a standard BT line straight into cat 5 I cant see what use this would be.
I always run double wall sockets, this the allows for telephone and data, I also usually find that working out how many people are lily to be working in each room, then adding at extra point is a good idea, this allows for printers etc to be hooked up, and the user can decide which point to plug there machine into.
Dont skimp on buying cable, you will no doubt easilly eat into/use a 1000ft box of the stuff by the time you allow for cuts and wastage, and at £27 a box its cheaper than buying more smaller runs.
Looking at your plan, I would look at doing 4 cables to all rooms, it just like plug sockets, there are never enough. Unless these office rooms are hoebox size you need to allow for two pcs/printers minimum and then two telephone/fax machines...
Dont whatever you do under price this job if it is for a customer, cable running is often a pig of a job, that will easilly eat into profit margins if you let it. Oh and its a lot easier/nicer to do if there are two of you.
hope that helps...
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You will need one of these if you need to do patch leaads non boxed terminations:
http://www.tlc-direct.co.uk/Products/CXTOOL.html
and one of these for the back of the patch unit and cabling into the junction boxes.
http://www.tlc-direct.co.uk/Products/GPT107.html
You can get plastic ones but they aint worth the bother... IMHO