At lower levels the 'standard' meta is dual lanes in both safelane (long lane) and offlane (short lane). Sometimes you will have a jungler, sometimes you won't.

At a higher level the most common lane setup is two supports and a farming carry (ADC in LoL I think) in the safelane, a tanky or hard to kill solo offlane, and a fairly farm dependant mid.

Heroes with stealth and burst damage that you didn't mention would be phantom assassin, nyx assassin, maybe spirit breaker, storm spirit (harder to play well), legion commander with blink or shadow blade, Templar assassin with blink dagger, tiny with a shadow blade or blink dagger.

For learning items, check out the eSports section on dotabuff.com to see what professionals build on your chosen hero. Think about why they vary it (bkb in this game, linkens in that game, force staff vs blink etc.) and try to apply the same reasoning in your games. It is best to spam the same hero and only change the item build slightly from game to game so you can more easily analyze the differences the items give.

You may know this from LoL but the most important things are last hitting/getting gold and not dying. KDA matters less than towers. Objective based gaming is important: grt a midgame pickoff or or two? Take a tower or roshan.

Learn about stacking, pulling, double pulling, where to place wards, how to deward pull camps, how damage types and silence/slow/stun works, how armour and magical resistance work, how illusions and summons work and so on.

Spam one hero at a time so you can limit the variability of new information: if you don't need to relearn a hero every time you can focus on all the other new information.

There is an argument to be made for playing every hero once before spamming a single hero, just so you have an idea of what each one does. That's up to you, I didn't.