Hi mate,

Good for you to get a bargin on your hybrids and hopefully I will answer your 4 questions.

Question 1 & 2) As how a hybrid will effect your game. The reason hybrids are greatly used now, is that with a hybrid, you have more options on where to use it. A hybrid in your bag is just another tool to help you obtain good results. They help in 2 ways, with first one, they have extra weight at the back of the club face. This allows you to use it in rough terrain, as if you use an iron would probably get caught up and change the swing path / face of the club hitting the ball. So that you dont control its direction plus loss of power hitting the ball which will loose you distance.
The second benifit which you will see is what you have said increase in distance. This however will depend on how you swing the club. Most people see the hybrids as fairway woods, which is understandable as they look like one, but this is wrong. They are still an iron at the end of the day but with a bit more weight further back, so to hit one dont change your swing for it just hit it like you would with your 3 & 4 normal irons.

Question 3) Does it show weakness. Well this is a big NO in fact I would bet that you will drop a few strokes of your game because of it. Due to the fact that it could save you in problem areas. Just think of the options it would give you.

Question 4) Whats in your bag. Well I have a hybrid that replaces my 3 iron but I still carry my old 3 iron in my bag because of more choice in distance when I am playing. Infact I have removed my 7 wood from my bag as I get better control with my hybrid for shaping shots.

Hope it helps

Cheers
Mark