CAT6a may be worth looking at if you really want to future proof it without laying optic fibre. Costs for 6a are more but will handle 10GB. I would steer clear of CAT5E as a backbone as that really is slow technology now. CAT6 as an absolute minimum.
Midland 331 will tell you it doesn't take any longer to pull 5 cables than it does to pull one and as he said, make sure you have a professional cabler install it. Sparkies are often not up with bend the radius of the various cables and you really don't want the data to slow down when it hits a too tight a corner.
If in doubt just remember to do it once to do it right. Spend a bit more now to save upgrades or congestion in the future. Replacing the hardware is easy. Replacing the cable is a PITA!
Good luck with your dependence on the Cloud. I would suggest a second ISP, preferably from a different exchange, and a dual WAN router. If your ISP, phone line or exchange go down you are effectively stuffed.