what f stop would you recommend in conjunction with using bulb for fireworks?
Well you want as best depth of field as you can get but you also need to know...you are aiming very far away so depth of field is not so much an issue. Having said that you should still keep your apeture to about f8 to f16. I say that becasue generally, most lens would give you the best quality at this f-stop.
I have had success with using f8 at about just 4-8 seconds. It is hard to teach this...as you sometime have to "feel" the shot and know how long an exposure you would need to get how much "tail of the firework" for example. It is only with practice and yes it can take you quite a few firework to get it right...and as you know...that is rare thus it can take you years heheh...but so far....you should be able to get some pretty good shots with just exposures of about 4-8 seconds. Some would open up longer as they want to capture as many burst as possible but the problem here is...it can end up looking very messy if you have no idea how the firework will be choreography right? I mean....practice run? how many can afford that heheh...so usually...there is abit of luck to it lah. I have shot alot of firework for many year and I have many times gone home with shitty stuff heheh...or maybe less then 5 good ones out of like a 50+ shots. Yes...if you are lucky there have a long display, you can get as many as 50+ shot off that is if you fire them at about 4 second or so. Now my camera has the speed setting of 4 second for me to choose right? Well I still use bulb. I count with my mind instead..this give me the flexibility to change my mind and add/take away another second or more if I feel the shot requires it. I took care of all my setting details so that I can concentrate on taking the shots and timing it without having to worry about anything else. I am sure others here have their own way lah.
Fix your camera on a tripod, focus to the point where the firework will take place, don't try to use autofocus, the af sensor can go crazy trying to focus and track the firework you can end up with fuzzy shots. Look not at your camera's viewfinder after you have it set up...instead hold your remote control and look at the sky for clues as to when to fire off your shutter. Peep thru your viewfinder only when you want to change angle, zoom length..etc and then just snap as you see what appears by looking at the sky again...And hopfulling with some luck you get a few good gems for your effort.
Abit more about focusing...well the begining of any firework is usually very basic as the choreography goes...it build up you see to pull everyone's emotion along...so the first few seconds is great time for you to get a good idea as to where thei firework will up in the sky..now try to focus manually ( remember to set your AF to manual so it does not jump all over the place once you set it up) now once you get a sharp view, you are set..so just shoot. Use a zoom so that at times you can zoom closer for a tight short or zoom out in case the firework spread out over a large width and you need to capture it.
Also...do your homework...try to find out as much about the firework, where it will be fired, what kind of firework pattern to expect, sometime they also tell you how high it will get..etc.
Just some tips lah...you will have to learn as you go along. You will make mistakes for sure but the experiences will make you get better at it in due time.