I know it comes from malted grains!
But..what are the most usual ingredients to includes to get a malty flavor into an ale? Or not to includes if you prefer the hops/yeast tastes!
Does yeast and temperature have a real strong impact on malt notes?
Everything you listed affects the malt presence. Different grains produce mild to big malt flavor--your caramel/crystal malts, roasted/toasted malts, etc are all designed to emphasize certain flavors and aspects of the malt. The difference between 2-row and 6-row can change the malt presence. Most commonly, for pale ales and such, people will add crystal to enhance the malt presence. Stouts and such almost entirely rely on the malt to make the beer.
Yeast strains are designed to either bring out the malt, the hop, or both. A Califonia style yeast will be subdued and let anything play by itself, mostly hops. Conversely, a british yeast, or irish yeast will be designed to bring the malt flavors to the front. I think, in most of these cases, the hop is only there to balance out the malt sweetness but not add any flavor or aroma.
The temperature at which you mash will affect the malt presence. Not as much as grist bill or yeast choice will, but if you mash at a higher temp, the sugar will not be broken down as much and thus the malt sweetness, body, and flavor will stay around.
So the answer is: everything you do when you brew can change the malt presence. There is no short and simple answer.