Well I think they are all sensible discussion topics, but where are the other 69 we are promised ?
A troll's guide to 100 useless forum topic ideas
You forgot:
"Anand will beat Carlsen in 2016"
"e4 vs d4"
"Why do people disconnect?"
"Stalemate should be a win"

Should I prefer dark squared knight over light squared knight?
I like this one.
+1

- What are king's main weaknesses?
- What are king's main strength?
Are good questions. If the king is attacked he is obligated to get out of check, thus greatly limiting the defender's options. Mate ending the game is the source of most of the king's weaknesses and king safety is a very important positional feature and real (or imagined, as in the case of most Sveshnikov positions) king safety is to be taken into consideration when embarking on an attack.
The king's movement apart from castling is the opposite that of the knight: instead of the closest square not on the same rank, file, or diagonal it is simply the closest square in any direction, period. His placement in an endgame is typically decisive, though usually king activity on both sides are equal and piece activity and pawn structure tend to overshadow it as that's where the imbalances typically are, two equally active kings is a balance.
Back to the opening and middlegame: yes the king requires adequate defence, but he defends the squares around him, some pieces may block potential pawn targets, or add extra defence to them. Since you need more attackers than they have defenders you really need to prepare a king attack well, and then your goal should be a superior endgame or positional advantage as you should assume best defence.
Castling also connects the rooks sooner.
If you have to ask then yes, the King's Gambit is too advanced for you. I'm in a theme tournament and it gets very hard to handle especially as white. I like the Falkbeer better than the Fischer Defence since the Fischer Defence seems easy enough to botch even if it's theoretically excellent for black (Spassky defeated Karpov when Karpov used it.)

Vox Populi ^^^
32. Why is a4 a better option than a3 against someone with telepathy?
33. Should there be capital punishment for people who cheats?
34. Is it true that in SA they chop of your hand for stealing pieces?
35. Am I the worst player in the history of universe?
36. What is the correct pronunciation of Anand? Aanand? Anaand? Or Ananda?
37. The reason i suck is because i dont play as black as i often as i should?
38. how many moves can you think ahead at a time?
39. is alekhine's defence strong against a mugger?
40. how to tell the difference between zwischenzug, zugzwang, and zwschenschach?
41. what's your favorite square?
42. is it normal to have a crush on Stockfish for a beginner?
43. what is a good title for david hasselhof's biography? plyboy or knightrider?
44. is chess turing complete?
45. do you dream in chess?
46. why did i say j'accuse instead of j'addube?
47. if you suffered spinal and brain injury with car falling down a cliff to ocean should you check "i am in vacation"
48. be honest if you played tactics in blind mode
49. lol 32. kf4+ a3 33. Ba1+ ??
50. how to start a chess club for 1300-1400 range?
51. is it true you go blind if you play chess by yourself blindfolded
52. favorite chess paradoxes?
53. favorite fianchetto that correlates to your incline for specific diagonal?
54. why dont they blurt out at fast food joints: do you want chess with that?
55. how to stay motivated in chess but not being an addict
56. is it safe to play chess and drive if you dont have airbags?
57. how to play backwards chess960 with castling rules blindfolded in touch move with board flipped?
58. i played 10 game and dropped to 390? am i the worst player from croatia?
59. what if a pigeon died in correspondence chess?
60. what wireless carrier to use to txt in correspondence chesS?
61. mac vs pc in blitZ?
i give up.

Good chess technique...pinky finger extended? After politely asking for a resignation, a player should commit seppuku if the opponent declines. New chess variant based on existing something or other.
62. What is a troll?
63. Is Monopoly better than chess?
64. I am the most awesomest person in the world.
65. Why the bongcloud opening is the best in the world.
66. What's 9 + 10?
67. Forum for trolling
68. Erik is stupid
69. Silver membership problem
70. Live chess vs online chess?
71. Is COMPUTER-4-Impossible better than Deep Blue?
72. Who is the best chess player ever?
73. Can you beat Paul Morphy with pawn odds?
74. Why chess is a horrible game.
75. The last one to post is the BEST TROLL on chess.com
76.
77. Check out my YouTube channel
78. I am dead
79. Troll
80. My friend is so good he can checkmate you in four moves!
81. Where is [Chess.com user]?
82. Why mods are stupid - MOD
83. Can I reach a rating of 1000 within a year?
84. I love you [Chess.com user]
85. Burning wood pieces
86. You are stupid
87. This forum topic had been locked
88. My IQ is 160 but my chess rating is only 800?
89. FIDE vs USCF?
90. Bobby Fischer is an idiot
91. Bobby Fisher is an idiot
92. Why was the game drawn?
93. pi
94. Go Manchester United
95. Is chess won with right play or drawn?
96. Why castling is bad
97. Opponent is a cheater
98. Weird pawn move
99. 1000 reasons why chess is bad for you
100. A troll's guide to 100 useless forum topic ideas
24. do you think king's gambit is too advanced for me?
25. n00b question: is it true king cannot move first legally?
26. which format is the fastest to reach 2100 rating?
27. where is carlsen?
28. why is carlsen?
29. when is carlsen?
30. HAL vs Eagle Eye who will win?
31. Fischer v. Kasparov...in a cage fight
And so on...