This thread is extremely helpful: http://community.myfitnesspal.com/en/discussion/10103966/start-here-the-lcd-launch-pad#latest

From my experience:
Don't pay attention to calories for the first week or two...it's hard enough eating keto carb level at first.
Have a meal plan that's easy but also enjoyable.
"Keto Flu" is 100% avoidable as long as you get enough salt.
Enjoy. It's actually a really easy way to eat and the benefits are wonderful.

Ya regular salt is fine. Depending on the type/quantity of vegetables you eat, iodized salt can make it in the rotation as well. Some people have good luck using "lite salt", which give you potassium chloride as well as the sodium chloride.

Keep it simple. Enter your stats in mfp for your desired loss and set macros to 5% carbs, 20% protein and 75% fats. Later on you can tweak your macros to personal preference if you choose. The important part is to start. You lost weight before via calorie counting. You'll still be monitoring/keeping to a deficit in keto. Your macros are simply set differently. Calories still matter. Keeping carbs low should help with things like minimizing or eliminating cravings if you have them. Fats tend to be satiating for many so the high fat part keeps some from being hungry all the time. True for the lower carbs also. Higher protein seems to keep others satiated so that is a part of why some people may up protein.

You'll find your "sweet spot" as you progress.