ummm i have a friend that has taken care of horses at a farm since she was 5. she said she would help me if i had all the equipment thats why im asking. she is 34 now.

Well then, ask her what equipment she prefers.
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With a western saddle there are several areas to look at: the width of the tree, is it full quarter horse bars, or partial quarter horse bars. How much withers does your horse have, what kind of saddle pad are you using, is it a thick pad, a cutback, a cutback built up. The pommel of the saddle should not touch the withers, you should be able to put your hand with the little finger on his withers and have space enough for your other three fingers between it and your saddle. Do you have someone who can look at where the saddle sits when you are in the saddle? As I said you do not want the saddle to touch the withers.
Another thing to look at how is the saddle rigged, is it a full rigging, a 3/4 rigging, a centerfire, all of these will make a difference and it is based on your horses confirmation.
As for lunging a horse, nothing will take the place of your hands on the reins. On a western horse you do not use a cavason the best tool is collection and that you can only accomplish with your legs on his back. As for a bit, I use a low port sweet mouth usually with a copper roller or spoon. Stay away from aluminum bits if you can, they will cut a horses mouth quicker then a spade bit. The average horse needs a 5 inch bit. If he is a large horse and by that I mean really stocky, 16 hands a big horse, then you might need a 5 1/2 inch mouthpiece. However if it is an Arabian it is possible that you will need a 4 1/2 inch mouthpiece.
I would go to a reputable tack store and talk to them or if you have a saddle maker near by, they can help you with fitting your saddle. Don't try to combine Western tack and English tack, the two don't mix. Totally different points of contact and riding style. I am not saying that your horse can't do both, just use totally different tack, including bridles.

the saddle is a half quarter horse with a thick pad. I can get the saddle in the right spot but it slids back by the time i walk him arround. what do i do. also how do i get him to collect. also im having some trouble getting him to let me open gates. what can i do. he dose not know hoe to side step though and i dont know where to push.

Saddles cannot be fitted online. You need a professional saddle fitter to come to you and fit the saddle for your horse, and help you find a new one if needed.

Collection isn't just something you get a horse to do - it takes years to learn to do properly both for the horse and the rider. You need a good dressage trainer for that.

You can read here about what true collection is technically and about the dangers of false collection - and, please, don't try to force your horse into one. It won't end well.

::: Sustainable Dressage - Collection & Its Evasions - True Collection - What It Is and How to Achieve It :::
::: Sustainable Dressage - Collection & Its Evasions - False Collection & Evasions :::

For a horse to allow the rider to open gates, he first has to learn to stand still, to yield his fore- and hindquarters with precision, to sidestep, to take a step with one leg only, if needed. All of this is taught from the ground first. And the rider has to know how to ask for this - horses don't have built in buttons that can be pushed for an uniform reaction.

^All of this. The questions (which seem to be numerous) and issues that you have are best dealt with by professionals, in person.

Please get a trainer to work with the both of you. From your questions it's obvious that you don't have the experience to teach him these things, and all I see is an accident waiting to happen. Save yourself the heartache and do it right the first time around.