Of course sodium can cause edema (make you hold water), especially if you eat more one day than you're normally used to consuming. The truth is that there's a crap-load of sodium in just about everything, especially processed and frozen foods. The recommended daily allowance is around 2,000 mg's and most people get that at breakfast! So, yes you should just be aware of your sodium intake and don't just throw all caution to the wind, but if you're going to have it try to get more naturally occuring sodium than the iodized type that's found in processed foods.
Sea salt is excellent and it tastes so much better than the regular white table salt. The normal table salt has lots of additives to keep it from caking, it's heated to high temperatures and is bleeched to make it pure white. Sea salt like Himalayan salt (which is usually pink in color) is harvested naturally from ocean coastlines and is choc full of healthy minerals.
And yes, hydrating with water should be your #1 concern no matter who you are. I choose spring water over distilled most of the time just because too much water can also leach minerals from your body. One mineral that's super important to help balance out your sodium levels is potassium. So the next time you're reading a label...let's say Protein Pudding for example...you might see like 400 mg's of sodium, but you'll also see 300 mg's of potassium to help balance out the two.
Too much sodium in your diet might also lead to hypertension (high blood pressure) although unless you already have a history of HBP it isn't a huge worry.
Bottom line, just be aware of how much you're eating and read labels. It ain't gonna kill you, but it's always better to make good healthy decisions.