The minimum dosage of EFA oils is one tablespoon a day. Not sure what the max would be, but you want to be sure to only take about a tablespoon or two at a single time so it digests fully.
It's also a good idea to take lipase (pancreatic enzyme) with it too when you first start taking it, especially if your digestion is compromised, just for a couple weeks until you're sure your pancreas is doing its job properly. When I first started taking flax I burped it up all the time. very annoying!
If you like the flavor of both oils, then alternate. Variety is key to balance, even if one food seemes perfect (and hemp has a great balance to it), having both often gives the body options that the one alone, however good it is, just won't.