Most of our payloads are under 2.5kg so we can fly on smaller 1000g balloons. There is a shortage of helium currently, but we prefer it over hydrogen because it is an inert gas.
If you like to volunteer your time, the US Dept of Education will be making an announcement in the next few weeks for a CubeSat Challenge. First stage is building prototypes - which of course could be launched in a HAB or High Power Rocket.
You can track a number of our flights on https://aprs.fi KK6UUQ. Here is a launch from Saturday that we did with USC and LA Unified School District: https://aprs.fi/#!mt=roadmap&z=11&call=a%2FKK6UUQ-11&timeran...
If you are into this, check out https://magnitude.io
When we did our launch, we originally planned on a Hydrogen launch because we were informed of the Helium shortage. We bought all of our equipment based on Hydrogen being the gas. This is important for those that do not know as Hydrogen equipment has specific fittings so that it will not work with any other gas equipment. This is to prevent accidental/unexpected use of Hydrogen due to it being so volatile.
When we showed up to pick up the tank of Hydrogen, the employee really hesitated selling us the tank of gas. He explained that the flames from Hydrogen gas is colorless, so we could be on fire before we even saw the flames. The flames only display color when the flames catch other material begins to burn. He ultimately exchanged all of our Hydrogen equipment for Helium, and sold us the tank of Helium.
I should note that the balloon only came down because it was designed to burst at a certain altitude and return under a parachute. Other designs that are meant for long or indefinite missions can last for weeks. As I understand it, other than lifting gas leakage the main limiting factors are energy (solved with solar panels, batteries, and smart usage) and balloon integrity under bright sunlight.
As for quick deployment, perhaps there are ways to do it, but it took our (admittedly inexperienced) team of 15 or so about an hour to string up our payloads, fill the balloon to the right volume, and release it. Lots of fun, though.
Lifting a helium tank would require a very large balloon. Larger than the single helium tank could fill on its own. These tanks are very heavy.
This would still make it a very practical kit and a good idea. It took several hours of looking online for local locations to purchase our gas, so including the pre-paid coupon would be a big plus. Especially for groups that might do this one time only.
Also, realistic bursting altitude is closer to ~60,000ft for most balloons, just FYI.
2. We didn't purchase any specifically, but given we were an official campus organization, we would have likely gone through them had something like that happened. Given the rural area we were launching from, and where we knew it would travel, the likelihood of this happening is close enough to 0 that we didn't have to worry.
AMA about it!
Look into APRS and how to build (or you can purchase one) an APRS GPS transmitter, that'll be the most important bit as if that isn't working, you'll very likely never find your balloon. Once that's working, you can use a site like aprs.fi to track the balloon in realtime from a laptop/mobile device and follow it as it flies. Keep in mind it could VERY well travel over a hundred miles. We launched ours from Decorah, Iowa and we had legitimate concerns about wind patterns causing it to fly as far as Chicago.
I'd also recommend looking into how to build a "Fox" and how to foxhunt. That's a big part of these balloon launches too! Once you've gotten as close as you can with GPS (once the balloon falls below a certain altitude, relays will stop picking it up on APRS so you'll have only a general idea of where it fell), you'll want to use a directional (for instance, a Yagi-Uda) antenna and a handheld radio to try to directionally locate the fallen payload. Funnily enough for us, we didn't have to foxhunt since it landed in the middle of a guy's field, when we parked across from his house, he asked what we were up to - he was friendly and just curious - and we told him, he said he thought he saw something shiny in his field and assumed it was garbage blown over from the road or something and let us come over to look at it. Turns out it was our balloon! The shiny thing was the radar reflector.
Then, put whatever you want in your payload really! We used a paint can stuffed with foam (it gets REAL cold up there, like -100F, keep that in mind!) and shoved sensors into it and attached a 360 gopro to the side. You can find stuff about how to build temperature/humidity/etc data logging setups that log to an SD card. I'd also recommend that after you retreive your balloon, go to some place like aprs.fi and download the GPS track data from the launch! Those sites don't keep it around forever, you'll definitely want a copy for yourself.
You can get the balloons themselves quite easily, and welding gas suppliers should be able to get you a cylinder of helium.
You can see almost every balloons with a ham radio payload currently in the air, in real time at https://tracker.habhub.org/
One thing I really would like to do is get a stabilized camera and experiment with some rigging that reduces payload rocking. A steerable parafoil recovery is also rolling around in the head. All of these ideas exacerbate the procrastination situation lol.
I still want to do another launch with improvements learned from the first launch. All of the improvements definitely require a much larger balloon (meaning more expensive). I now have friends with HAM license so we can use a radio for real-time data transmission. I have my Arduino flight computer with all of the sensors completed. The camera stabilization was the biggest thing I wanted to solve. Many ideas rolling around in my head as well. Might need a 3rd or 4th flight to finesse, you know, for science!
I've only tracked one once, using an old scanner and antenna, but I'd like to get a decent collinear antenna to use with an SDR.
Of course he sells stuff to do it, but there are many balloon flights documented on that site too. Some of them have circumnavigated the Earth more than once!