You will get different opinions on this, but ferts in small amounts will not hurt shrimp. Especially the hardier species. The thing you need to watch out for is copper, which can also be found in foods that are feed.
Plants get nutrients from the water column, with the exception of swords/crypts which obtain a majority of their nutrients from the substrate. So Blyxa will need the addition of liquid ferts added to the water. If you go with low light/low tech tank, then very little will need to be used.