You need to do more homework before cutting anything or building anything and its a good sign that you are asking the questions here.Have you seen the MDF zoned vacuum tables that are offered as kits which allow you to build your own small vacuum table?They use ball valves and sit on a flat bench top-to which the vacuum holds them.A shop Vac is sufficient for a hand router and may be enough for a small CNC if the parts cover a large enough area.The area is important because the more area subjected to a vacuum-the greater the clamping force and the chance that the piece will stay put.The ball valves are an important part of the concept because unless they are pushed open there isn't an air passage and the vacuum beneath the job is more complete.Your idea of using pegboard is almost certainty doomed by the amount of leakage it will allow around the piece you are trying to machine.You also need a sufficiently rigid surface to keep the Z axis where it believes the job to be located and pegboard will very likely allow the job to move below where it is expected to be.I am trying to remember who makes the kits for the small tables I have seen.