hey ^^ Welcome aboard :P I'll try to clarify that for you
1. yes, practice games are usually finished very quickly against bots, but that's the standard for experienced players, keep in mind that in this game there is a very huge difference between players of different skill level, and also a lot of variety (instead of just players who are new and players who know the game... I can compare the skill level to chess. there just are a lot of platforms to reach ^^. If you're unfamiliar with the genre, don't push yourself too hard, people have been playing this for years :P)
2. ALWAYS use your starting gold :P It's the starting advantage that you should use to get the upper edge and win your first grounds against the enemy (or make the first kill, best case scenario - althouhg making him go back to heal is very valuable as well, as you get to kill minions and gain level in the meantime).
The Doran's items are great for starting, and I strongly suggest you use those + a health potion untill you feel comfortable enough for a more complicated build. (it's the risk vs rewards system. Doran's is the safest way. Other opening involve more risk but greater rewards if you succeed. Example: you buy an item component which doesn't really give a lot of stats (saphire crystal). But then, if you still manage to get a kill, you can get Sheen very quickly, which is a recepie item, and at this point you'll definetly have an advanatge. But you started with lesser stats. SO if you don't feel like you can outplay people just yet, go for the safe way.
3. yes, and it is very important. Usually your "ultimate", as the 4th ability is called, is very gamebreaking and allows a whole new layer of play. Ashe as an example: you can stun people from an infinite distance, if you aim well. You could support battles all over the map :P
4. For each champion there are tons of different builds and strategies. Not to mention when you get really into the spirit of the game, you'll consider not just strategies that make you strong, but also ones that counter your enemies.
A very generic build for Ashe involves Volley as max, (this still means Ultimate takes higher prioryti if available), your E skill once and Q afterwards. This allows you to scout the map with your level one skill, and put more points into frost arrows which allow you to kite. Which brings is to 5...
5. Kiting. This is reffered to as the ability to deal damage from a distance, while maintaining this distance. In ashe's case, frost arrows. You fire an Arrow, run a bit back, fire an other one, move, fire, etc. Your oponent is slowed and with good boots and high level in forst arrows, you are able to move the distance he moved + some extra giving you time to fire in between. Thus you deal damage while keeping yourself at a distance, safe. There are other champions with similar mechanics.