Hi and sorry for the late reply, I haven't checked the itch.io page in some time, which I hope you understand as you're also here from the play store :)
There are already descriptions for parts if you click and hold on them in the inventory menu, or are you already aware and did you mean to improve / make longer the existing descriptions? Which would be a good one as they're indeed a bit short.
More parts, including more fuel related stuff will be released after 0.31 (first there'll be an update or 2 fixing bugs and improving multiplayer).
The way blocks are connected does feel a bit fragile yes but unfortunately it's the only way due to some issues with physics limitations.
The satellites dissappearing on levels 7 and 8 has been fixed in 0.31 (thanks for letting me know!)
I really like the idea of a tech tree which is also why the existing parts have tiers assigned (T1, T2 etc). This will likely take quite some time to make so maybe towards 1.0
Mining and selling/ trading scrap for parts were both a bit rushed and are planned to receive a rework in the near future.
Multiplayer will receive a 1v1 Duels gamemode next so hopefully that'll make it a bit more interesting.
Thanks for your suggestions, I took note of all of them so you can expect to see some back ingame soon! :D