Thanks for the hips and shoulders tips..will try to adopt that in future deadlift forms..

However, I argued that you don't arch your back during bench.. I've seen various trainers and articles and even try it out myself to slightly arch during benching..this not only imitates the decline movement which utilizes less shoulder stabilizing effect but also closing the distance between the bar and chest which makes it easier.. it also has been adopted in powerlifting style.. maybe for bodybuilding, that's the case of not arch to maximize muscle exhaustion by not locking out and not touching the chest.. But slight arch won't hurt much though..

Here is some of the tips found on the stronglifts 5x5 regarding bench pressing tips:

5 Tips to Improve Bench Press Technique:
1. Keep proper arch to your back, an arched back creates a decline pressing position and everybody knows you can decline press more weight then incline or flat. It does this by giving your body more leverage and cuts the total distance the bar has to travel by nearly half.

2. Keep the proper grip width, If you grip too narrow you won’t be able to lift as much as you will be recruiting more triceps and lest chest, too wide and you will not be able to do as much weight, and you will get less travel. You want your forearms perpendicular to the floor when the bar is touching your chest.

3. Lock in your back, I picture my lats squeezing together so hard that they actually pinch the bench. If you can keep your back tight and strong it will provide the optimal platform for when you are pushing all of that weight off of your chest. Also be sure to get your rear shoulders as flat to the bench as possible, again this just adds to the strength of the platform that you are pressing from.

4. Keep your feet in a wide stance, this will give you more stability and a stronger platform to push from. There are two placement positions that can give you great results, one is to keep your feet flat to the ground and the weight of your legs positioned on your heels. The other placement is to put your feet as far behind you as possible even as far so that your feet are nearly directly below your glutes and put all of your leg weight on your toes. The increased leverage can help to increase your bench pressing power and help you to add weight quicker to your bench press.

5. Get the proper grip on the bar, by doing so you will gain more power and control of the weight. Put the bar in the palm of your hand and squeeze the bar tightly, I have heard that if you imagine that you are bending the bar like you can a raw spaghetti noodle you will increase your power in the bench.