I am not personally familiar with any salt systems for above ground pools, but I know that you can consult your owner's manual that should indicate the water chemistry targets for proper operation of the system, including calcium. If you don't have your system yet, you might try downloading the manual from the mfr's website.

"...will it help keep other problems away?" No...Hardness will not keep away algae and it will not sanitize your water, keeping the icky stuff at bay, so be sure to follow duraleigh's advice to keep your chlorine in proper range based on your CYA/stabilizer reading.