Maintaining your weight usually involved keeping to whatever you've done to lose weight and gradually relaxing the rules. (eg, add 50 calories to your daily allowance each week)
Monitor your weight and expect a small increase with each change. set a bar that your weight is not allowed to go higher than (2 percent of current body weight is reasonable), if you do cross it, reinforce your original diet and change different parameters or alter them more slowly.
skin: Abdominal exercises will help control it to an extent, also allow your skin possibly a year or two to firm up of it's own accord.
Wouldn't suggest creams or lotions. didn't do jack when I tried them a few years back.