I use the API master freshwater test kits, and usually get mine from
www.BigAlsOnline.com, about $30. And you definitely need to add on a kH/gH test kit if you're planning on trying to adjust your water hardness and pH- quick water parameter changes aren't good for fish, so you'll want to make adjustments slowly. I recommend shooting for a target kH and gH for your pond (probably in the neighborhood of 5-7 dkH should be enough to maintain a stable pH) rather than trying to chase a particular pH since there are so many things that can affect water's pH (dissolved gas levels, organic decomp, etc), and it's really the total dissolved solids that have the most immediate and dramatic impact on fish internal systems.
Another way to help maintain a stable kH is to add some carbonate-based substrate (like crushed coral/shells/aragonite) into your filter. Depending on what type of filter you're running, you might even consider replacing some sand/gravel with a buffering substrate.
The big problem once you start trying to adjust your water parameters to something different than your tap water parameters is how to maintain stability over time, especially factoring evaporation into the equation, since the solids won't evaporate out so you'll always have to test your parameters to see if you need to add any more bicarbonate or if you actually may need to lower your kH/gH with a water change due to buildup over time.
Whether or not to keep salt regularly in the water with freshwater fish is an ongoing debate across the fishkeeping hobby. Some people do, some people do not. I personally do not as I always have live plants in with my fish, and salt isn't the greatest thing for most plants. I use salt only temporarily for medicinal purposes, and then do big water changes to remove it when I'm done.