Frankie,
If you are going to intentionally go into a situation where you are going to be sweating heavily, it wouldn't hurt to have some means of replacing your salts. Since you have asked about packing salt in your PSK, though, I assume that you are referring more to a survival situation. In that case, while it wouldn't hurt to have the salts available, I'd be careful about taking them, or about eating or drinking anything salty. The salts are going to make you thirsty, and you may not have the water to spare.
Speaking of having water to spare -- in a survival situation, be sure to do what you can to keep your need for water to a minimum, such as staying as cool as possible, travelling at night (if at all), keeping exertion to a minimum, avoiding drinks that make you lose water (cola drinks, coffee, tea, etc), watching what you eat, etc.
If you still wish to pack something for salt replacement, and can't find a suitable electrolyte replacement powder, or if the powder is more expensive than the salt tablets, I'd suggest just packing a few of the tablets. They won't kill you. As a last resort, you could pack some table salt (iodized would be better than plain), but you run the risk of taking too much at once and making yourself vomit. If that happens, you'll dehydrate yourself even more.
As for the paracord, you should be able to find the real thing without a lot of trouble. There are many places from which you can order it either online or by phone. One of my favorites places is
Brigade Quartermasters. I have ordered many of their products, and have been very satisfied. Their service is excellent. I also like
Cheaper Than Dirt. I have never ordered anything from them, but they have a good selection, and their prices are quite good.