I'm referring to LoL's drawings which appear when you are about to cast a spell and tell you your range where you can cast the spell and also show the area of effect, where the spell will occur, so you see where exactly you can place your spells or show you how far your skillshots will fly.
Should (or will) they be included in Dota 2? Or should players simply get used to the spells they use by themselves?

I personally think they help a lot with new heroes (for instance I never knew torrent had such long casting range), but perhaps it's then it erases the difference between total newbies and pros who have played thousands of games with each hero and know everything from manacost on each level to casting range from their heads.

What do you think?

maybe changes the game play abit, which takes out the element of instinct which i. e. you rely in your instinct if your arrow will hit the target dead on

Well it doesn't matter that much with skillshots, you always click on the final destination, it only tells you that it will go only so far.

I was talking about timing,not to shot creeps instead etc.

Well, i agree. T-up for this.

Warcraft III (and DotA) has this system already but i think it is missing the most important part of it - Timing! In one of the recent updates Icefrog included a visual timer on Dazzle's Shallow Grave. I think this is great as the extra information allows players to do more advanced moves when they can precily used timing. I played WoW for a atleast 4 years, i understand that DotA is a different type of game but the lack of timers (both for buffs and debuffs) really limits player's actions because it makes timing very relaltive and i want to maximize the potential of spells (especially when using chain stuns, or other types of disables).

This is an exmaple of how the system can be improved:

How about a timer on top of Enigma's head when she/he/it is channeling Black Hole? The same type of timer for Rhasta's fire lasso, batrider's ulti and it would help if there are timers for all channeling spells. Same goes for stuns or any kind of disable.

I think that you already said (showing AoE for spells) will be very helpful for new players. I won't mind it, but i think i know the area of effect of most spells by now as it is easy to learn . Valve will definitely include AoE of spells for the sake of helping beginners, and i'm not sure if they will include (more) timers. I think there it should be implemented as optional, meaning that you can turn it on or off (because some users might find the screen over-crowded).

Yes timers would help