Thanks for the feedback! Nice to make friends
1) If you plan to connect an external camera to the ipad, then no, don't get LTE. That's because iOS doesn't allow apps like wifibooth to access both the wifi and the LTE at the same time (independently), and since wifi is required to connect to external cameras, then the LTE cannot be used. If you plan to use only the iPad camera, then getting LTE + sim card means you can use the features like dropbox, twitter, email, live on the internet even without wifi. If in doubt, don't get it.
2) No you don't need the big one. 32GB is sufficient. Don't get less than 32gb though, because then it gets hard to update the iPad to new versions of iOS in the future.
Regarding what to purchase, I assume you mean in the wifibooth app itself. There are three packages in wifibooth that you can purchase, and you should only purchase one of them -- the one you need. This help article breaks down the differences:
https://wifibooth.com/article/buy/
Finally: version 4 of wifibooth is about to come out (in July I hope). This is quite a change! If you don't have a lot of time to invest in playing with the app until later, then it might be good to wait. But no worries if you cannot wait: all of the purchases are exactly the same, and the features are all still there in the new version.