Need to set up network combining wired and wireless multiple buildings

I am getting ready to move into new digs and wanting to set up my network in the following manner and need a bit of advice. Main house cable internet will come in with modum to a dlink router for both wired and wireless. desktop and a magic jack wired into router wireless for ipad and laptop. then run wire to workshop about 100' from house where a second magic jack and desktop will be set up (small biz out of workshop). I am pretty sure that the range of the router for wireless will reach to workshop fine for ipad but if not I will need to put a wireless up there too.

Next kids have a laptop running windows 7 but kids being kids and having had problems with self control on net in past I want to be able to make sure that I can turn them off from net when needed because 1. I do not want them running me past the data limits imposed by cable company and 2. keep them from sites such as those which got them in trouble in the past (kids are older and bought laptop for selves and pop will not go along with me confiscating it if they abuse internet privileges.

My questions are as follows 1 for the wired to workshop what type cabling do I need to get I already have a large supply of cat 5a that I have used in past to make longer Ethernet cables with when needed but I do not know if that would work for going from house to workshop or if I have to get something special. Best way to set up things so kids are kept to their limits on sites and amount of time on net. Any suggestions appreciated.