The 2-4x pump flow "rule of thumb" is a nice goal, but it is more applicable to industrial applications. Many off-road machines are lucky to have 1x. I have worked in the engineering dept for a couple different OEM's and one machine was only 0.3x! A reservoir serves three main purposes. First, have sufficient volume to allow all cylinders to be extended or retracted at once. (basically add up the displaced volume of all the cylinder rods) Second, allow air to come out of solution. In reality this is a slow process so ±20% changes in reservoir volume won't make much difference here. (making the oil go over a baffle works great though) And three provide some heat rejection, though if you do the calculations you will find plastic or painted steel tanks don't shed enough heat to really be of help. If possible have the pump suction outlet at least 1/2 diameter above the floor so you don't suck up any debris from the floor. I also like to have a magnet to pick up any fine metal particles to help keep an eye on the system health.
As far as the suction lines go it is tough to give you an exact size recommendation since a couple things like head level, oil viscosity, ambient temperature range, hose vs tube, etc. come into play. In general though keep the ID at least as large as the section inlets. Keep 90's to an absolute minimum - large radius bends in tubing or hose, or even 45's, are a much better option if you have the room. Don't put a valve in the suction lines unless you absolutely have too - they add a significant restriction and if accidentally left closed will instantly destroy the pumps. Make sure if you use hose that it can tolerate pump suction during cold start-up without collapsing.
ISZ
