bench

muscle weighs more then fat.
The more muscle you add to your body, the more you weigh. ;-)
If you are gaining weight while you are benching , it is a good sign that you are building muscle mass .

how many sets and reps?

i start out with 5 reps and 2 to 3 set.after 2 days i would be able to do 15 reps and 3 sets.

Its not really a good idea to do chest each day unless you are exercising every other major muscle group as well. In the long run, your chest will become disproportionately large compared to the rest of your body. It looks stupid. I only used to do chest once a week, but I would do a lot more than 3 sets of 5 reps.

If you are using heavy weights, then generally you want to leave a day between workouts so that your muscles can rebuild themselves. Light weight, high rep workouts dont usually require much healing time. If muscle is what youre after, this is how I would do it.

Day1: Chest, Triceps and abs.
Day2:Rest, Eat, and drink lot of water
Day3: Upper and lower back, biceps, forearms
Day4: Same as day 2
Day5: Legs and shoulders.
Day6: Same as day 2.

Repeat, but switch up the exercises you do on the next go around. Muscles become used to certain exercises/motions if you do them too much and they lose their effectiveness.

You'll have to use heavy weights, you should be able to do no more than 8 reps on first set and no less than 4 on the last, and make sure you have someone to spot you.