Yeah mate aim for less than 20 ppm for nitrates. Once fully cycled u prob have 0-5ppm.
Honestly I've had shrimp in WP worse than u have now in a high fert high co2 planted which survive fine. Some are hard like bullets.. like red cherries, mishlings, lower grade crs/gbs and wilds. The reason why I say this is because sometimes for everything to zero out can take weeks.. so if u have any of these spare, throw some in as pioneer shrimp (sounds better than test subjects) :p
If u don't have any PM me and if ur happy to pay for postage I have around 15-20 shrimp im looking to move on anyways. No charge on shrimp.
Algae on tank is a sign of cycling.. normally goes from brownish to green as it matures. Your right leave it for the shrimp to graze. High Nitrates cause conditions for algae blooms. Keep lights to a minimum to avoid an absolute outbreak but your water changes will bring down your Nitrates and therefore slow down the growth however this can be circumstantial. When it goes stringy thats the worst IMO absolutely sucks!
Also if u have IAL add a leaf or 2 to your bucket of tap water with an airstone and give it a few days before adding it to your tank. This will also help you and your future shrimp ;)
Good luck