What kind of table salt? Most table salts contain iodine & anti-caking agents- not good for fish. You should be using aquarium salt, kosher salt or canning salt. If you read the ingredient label, you will find out what is in the salt. Even some sea salts are ok- but read the labels, alot contain anti-caking agents as well.
In respect to water changes, you probably should be doing them daily to keep your levels of ammonia & nitrite low (less than .25ppm). This is where a test kit is especially important. By checking your levels daily, you can figure out how much water needs to be changed & how often. For example, if you get an ammonia or nitrite level of .50ppm, a 50% water change will bring this down to .25ppm. Another 50% water change will bring your levels down to .125ppm. In respect to the ich, slowly increasing the temp (over 2-3 days) to around 86-88f will be sufficient to kill it. The proper type of salt can be used as well. You can read the stickies at the top of unhealthy fish for more information on ich. Please ask any questions you may have or if you are unsure about anything!