I usally use dumbells. 20lbs each butterfly 10lbs each
Same thing with DB's as with BB's. Bring the weight down to the nipple area, not the clavicle. You have to have your hands a little closer because of the fact that your using DB;'s but be concious that on the downward portion of the excersies your bringing the dumbell to the lateral chest area, so that the inner portion of the DB is more or less on the sides of your breasts, not on top of them. Push DB's up and you can bring them together at the top if you want to give the pecs a good squeeze, but widen as you come down so DB's are on the sides of the breasts, not up in your clavicle area...
would it be a good Idea to skip the bench & butterflies and just work on my shoulders first?
No, continue to train your chest (and all of your bodyparts, for that matter) even when your trying to bring up a weak part.
I'm going to drop down to a light weight and just get use to the form.
then go heavier in a couple of weeks. is that a good idea?
Probably, yes. Form is the first thing you need to master, before focusing on strength gains. The last thing you want to do is injure your self. If you can do 12 to 15 reps with the weight your using then it is probably light enough that you can still pay a lot of attention to your form. If not, then I would lighten up for awhile while you get your form down to where it is automatic.
Is there any really good exercise for my weak shoulder??
There are lot's of good excersises for shoulders. I would not go heavy at all right now. It is easy to injure shoulders and they are thre kind of muscle that you won't neccesarily know you hurt it til' a couple days later.
A good excersise (or excersises, I should say) would be cable raises for shoulders.
Cable side raises: Stand next to the cable pulley (lower cable) so your left foot is next to it. With right arm, reach across your body and grab the cable. Use a light weight (so you can do 15 reps easily) stand up straight, with back erect and leaning slightly to the right. Start position is with the cable in fromt of crotch. raise cable across body and out to the side unil it is parallel with shoulder.
Front cable raises: are done with the cable at the back of your feet, grab cable. Stand up straight. start position is with cable at hip. raise arm straight up until cable is at shoulder height.
Rear delt raises are a little trickier: Form is very important.
stand with cable to your side. Bend at waist until parallel to the floor with kneesslighlty bent and back flat and erect (NOT slumped). Reach across body with arm furthest from cable and grasp cable. Start position is with cable hanging down in front of you as your bent over. raise arm laterally (like a reverse flye) until it is parallel with your back. If you can't help but raise your back up while performing this excersise, the weight is too heavy and you are recruiting other muscles.
These three excersisie will work all three heads of the deltoid. I still do them quite a bit because they are awesome for shoulders.
I suggest cables to start because they are easeir to control than free weights and this is a great way to bring your shoulders up to speed.
I would start with one set of each maybe 3 times a week, then work up to 3 sets of each. Eventually you will be doing a lot more 'volume' (total sets and reps for one bodypart) that you will only be able to trian that part every few days. Right now though, I would train shoulders 3 times a week woth one set of each excersise as a good starting point. Every couple weeks add a set and see how it goes.
OK
Bets of luck

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