I freeze the unmixed stuff. A lot of people use those Hydrapeak 32oz bottles with custom 3D-printed inserts. You can find the inserts on Etsy. They're supposed to keep the vials at a steady temp, even during the freezer's defrost cycle.
I've had that happen. I injected and pulled the needle out too fast. The liquid sprayed everywhere, lol. Make sure you count to 7 (or whatever your doc recommends)!
Wow -- congrats on hitting your goal and getting out of the overweight category! Someone mentioned body fat %... I've been using a smart scale to track that. It's not perfect, but it's great for seeing trends over time.