Please note that updates are not scheduled for specific dates and that SMC is not taking any new suggestions as of now.
Super Mario Construct is a Super Mario World-styled HTML5 Mario editor made by Luigibonus (sprites by Nintendo, AmazingAlien, Tristaph, Nitrogamer, Evan F, DeadFesh, SuperMakerPlayer and Smuglutena). It is intended to be a successor to Super Mario Flash 2 and all other SMF games, as Adobe Flash will be discontinued in December 2020. The name Super Mario Construct was chosen because of the ability to create (construct) Mario levels, to immediately show that the game includes a Level Editor, and that the game is being developed in the HTML5 game making engine, Construct 3
The game includes a various amount of Mario moves, including the spinjump, swimming, sliding and various other ones which are unlocked by power-ups such as the Tanooki Suit. Also, you can change your controls in the game under the settings menu or the pause menu. It also has minigames, where players can play minigames made from Super Mario Construct elements and a 1-Player Missions mode which is being worked on and yet to be released.
The level editor contains a bunch of elements you can use, the levels you make with them can be shared on Level Palace (accounts are free, Level Palace also is in no way directly affiliated with SMC). Keeping track of the latest updates and teasers can be done by joining the discord server (link below), Level Share Square youtube or by use of several external sources. (which can be found in the discord server)
For the guide, FaQ and Changelogs maintained by MrGerund, click this link, it holds a ton of information which can clear up several of your questions about Super Mario Construct. More up to date... you can also find the SMC update schedule of SMC here, this document also contains tons of useful links and information outside of update scheduling.
SMC also has an official discord server you can join by clicking here.