What I refer to when I mention "powers", is the abilities I am able to get in the game. You can find it by going to magic in the menu then to powers. From the beginning of my playing the game up to probably about the second to the last time I've played it, I've only had one power (Battle Cry). I want to know how to get more powers. I was able to get a power that enabled me to turn into a werewolf, but that came from one of the quests. Will I have to wait more while doing the quests to get a new power, or is there some other way? Do I have to use the enchantment tool?
How to acquire new powers
the-elder-scrolls-v-skyrim
Related Solutions
I don't think that there is any additional information in the quest journal about Miscellaneous quests (that is, specifically the quests that get filled under the "Miscellaneous" category in the journal). The one line in the journal is all you get.
(Which, yes, is a surprising choice on Bethesda's part. Most RPGs will give you a paragraph or two about any quest in the journal, but Skyrim seemingly doesn't for Miscellaneous quests.)
However, if you've forgotten the context of the quest (which, as you point out, is very easy to do), you can always turn on quest tracking for that individual quest. Make sure that quest tracking is turned on for the Miscellaneous category as a whole (in the left column), and then turn on quest tracking for the individual quest in the right-hand list. (And maybe turn off quest tracking for other quests.)
Also, don't forget that you can select a Miscellaneous quest and get a map location for that quest.
These will let you at least find the person, place, or thing for that quest, even if you can't recall why or what you need to do with them. In almost all cases, what you need to do becomes clear when you get to the person, place, or thing.
Is there anything that I've done incorrectly for my build, in that I shouldn't have tried to get the best gear midway through the game?
This is very subjective - what is considered an "incorrect" build by one player, may be "optimal" for another. If you want to make the game harder, focus your skill points and perks on non-combat skills: Speech, Pickpocket, Lockpicking, etc. You can also put skill points and perks on combat skills that you won't be using in combat. This will level up your character (which will make enemy level difficulty scale to your level), while at the same time, not make your character stronger for combat.
With the Dragonborn DLC installed, perks may be undone and redistributed at the cost of one dragon soul per skill tree.
At the end of the At the Summit of Apocrypha quest, you will have access to different portals (one for each skill) which allows you to clear and regain any perks in that skill tree, at the cost of one dragon soul. You remove all perks from a single skill perk tree and can use these reclaimed perks on unlocking any perks you wish, including perks taken from said perk tree. By reading the Black Book, Waking Dreams, you can return to Apocrypha and alter the skill trees whenever you wish.
Are there any hard quests that I've completely missed, or do you think that now if I start new questlines with my increased stats, the game would level up the difficulty for me?
It is subjective to state which quests are "Hard quests". Just have a look here for a list of all quests and see which ones appear to be hard for you. As for the second part of your question, the unmodded game only checks your current level and the difficulty settings in the options to compute how difficult the enemies will be for you.
Excerpts from UESP wiki's "Leveling - Effects of Leveling" article:
Various aspects of the game are leveled. This means that as your character increases in level, some enemies become more challenging but also the quality of the items you find becomes better. However, the leveling system in Skyrim has been altered from that used in Oblivion, in response to criticisms of Oblivion's leveling system.
Different locations in Skyrim have different inherent difficulties. In other words, some dungeons are designed to be too difficult for low-level characters to enter. More challenging dungeons are generally located at higher elevations, meaning that early in the game players may want to avoid mountainous regions. However, more difficult dungeons contain better rewards. In addition, some high-quality items can be randomly found even early in the game.
... Bandit NPCs are always a fixed level for their name (Bandits are level 1, Bandit Thugs are level 9, Bandit Highwaymen are level 14, etc). The player's level affects the range of possible bandit types generated within a bandit dungeon, and probably the frequency, but does not seem to affect the resulting stats except in a few rare cases. Lower variant bandits remain reasonably common even when more dangerous bandits are available.
v1.9 Patch - 'Legendary' difficulty
Patch 1.9 adds a sixth difficulty level: Legendary. It reduces damage dealt by the player to x0.25 and increases damage taken by the player to x3.
Mods
If playing on the PC, you could also make the game harder with mods:
The mod, Pluto's Improved Skyrim Experience (PISE) has a "More Intense Level Scaling" component. It makes enemies more stronger relative to your level, compared to the vanilla enemy scaling. PISE also features harder sneaking, more enemy spawns, harder enemies and an overhauled enemy AI. The mod, Path of Shadows, a major stealth overhaul mod, also makes sneaking harder.
Other mods that may make the game harder:
- DFB - Random Encounters - adds different random encounters from vanilla: Vampires, Falmers, Werewolves, Dwarven Spiders, Spheres, Centurion, etc.
- High Level Enemies - has a feature that allows certain or all enemies to scale with your level
- Deadly Dragons - overhauls dragons to make them more challenging to fight
- Balanced Magic - designed to 'balance' the game's magic spells - make the spells do damage and consume mana appropriate to your magic perks, and lessens the effect of abusive perks like the 100% stagger change of the 'Impact' perk. It also affects enemy mage NPCs, making them more challenging
- Auto-cast Racial Powers Plugin - "Auto-cast racial powers will activate for NPCs, both enemy and friendly, making fights much more interesting and adding a new element to prioritizing targets in larger fights!"
Creature mods that increase creature spawn points, number of spawns, and also improves creature AI:
(I recommend using only one creature mod, to avoid conflicts and other issues.)
Best Answer
There's an extensive list of powers and how to get them on the UESP site.
Most of these powers are racial bonuses (including Battle Cry, which means you were playing as a Nord), which means your selection of race determines your "starting power."
However, many are also rewards from particular quests. You can find links to the quests required for each power on the UESP page.
For instance, there is a set of powers available to high-ranking members of the Thieves' Guild, and there is a particular power only available for completing an optional objective during the Assassin's Guild quest line.
Certain powers are granted by activating a Standing Stone - do note that you can only have one stone active at a time, and not every standing stone grants a power. Some give only passive bonuses.
Additionally, certain "conditions" - notably being a werewolf or vampire - also confer powers as part of their effects.