Bonus Talent Achievements
Bonus Talents are gained through the gain of achievements in Mass Effect. Once you've gained said achievement, you must create a new character and you will be able to pick a one time bonus talent (skill) for your character. Unfortunetly these cannot be added to existing characters via New Game+ who do not have a Bonus Talent yet.
A trick to gaining most, if not all, of these achievements is pretty simple. Just get high enough level to unlock the said skill for use and then find a group of enemies (if required) to use the said skill on. Save before you fight the group of enemies and then kill them. Once they're all dead, reload that last save and repeat until you've gained the said achievement.
[AI Hacking Specialist] --- Unlocks Bonus Talent 'Reverse Engineering'
[Assault Rifle Expert] --- Unlocks Bonus Talent 'Assault Rifle'
[Barrier Mastery] --- Unlocks Bonus Talent 'Barrier'
[Damping Specialist] --- Unlocks Bonus Talent 'Shielding'
[First Aid Specialist] --- Unlocks Bonus Talent 'First Aid'
[Lift Mastery] --- Unlocks Bonus Talent 'Lift'
[Neural Shock Specialist] --- Unlocks Bonus Talent 'Medicine'
[Overlord Specialist] --- Unlocks Bonus Talent 'Electronics'
[Sabotage Specialist] --- Unlocks Bonus Talent 'Decryption'
[Shotgun Expert] --- Unlocks Bonus Talent 'Shotgun'
[Singularity Mastery] --- Unlocks Bonus Talent 'Singularity'
[Sniper Expert] --- Unlocks Bonus Talent 'Sniper Rifle'
[Stasis Mastery] --- Unlocks Bonus Talent 'Stasis'
[Throw Mastery] --- Unlocks Bonus Talent 'Throw'
[Warp Mastery] --- Unlocks Bonus Talent 'Warp'
Passive/Permanent Bonus Achievements
All ally related achievements require you to play through 75% of the game with that squad member. So if you get them late in the game, starting from that point you need to complete 75% of the game. So basically you don't want to do any side quests until you've got your desired squad members to obtain the achievements you want.
[Asari Ally] --- Stasis and Barrier recharge speeds reduced by 10%
[Completionist] --- Experience gain increased 5%
[Dog of War] --- 10% Health
[Extreme Power Gamer] --- All experience bonuses gain an additional 5%
[Geth Hunter] --- 10% Shield Strength
[Krogan Ally] --- 1hp/sec regen
[Long Service Medal] --- 5% Weapon Damage Bonus
[Pistol Expert] --- Marksman duration increased 25%
[Power Gamer] --- +10% Experience Reward Bonus
[Quarian Ally] --- AI Hacking and Sabotage recharge speeds reduced by 10%
[Sentinal Ally] --- Lift and Throw recharge speeds reduced by 10%
[Soldier Ally] --- +10% Damage Reduction
[Tactician] --- +10% Shield Strength
[Turian Ally] --- Overload and Damping recharge speeds reduced by 10%
Miscellaneous Achievements with Bonuses
[Distinguished Combat Medal] --- Unlocks Insanity Difficulty and Gamer Picture
[Medal of Honor] --- Unlock Hardcore Difficulty, Unlock Levels 51-60
[Medal of Valor] --- Unlock Gamer Picture
[Rich] --- Spectre Weapons available for purchase (Rank X available at Lvl 50+)
Free Charm/Intimidate Points
This requires much time and many playthroughs. Like pretty much every other skill, these also have 12 slots to fill even though you may not see all 12 right away. Now when you become a Spectre, you will automatically gain one of each. Beyond that depending on how you answer in dialogue sequences will net you points over time. So good answers will net you Charm and asshole'ish answers will net you Intimidate over time.
Infinite Paragon/Renegade Points
On the planet Feros, you are asked to get a card to access the garage. When you do the required task in the Turians room to get his data, you leave and are confronted by the secretary. She will feed you some info about talking to her in the hotel bar before you give the data to the Turian. Do so and she will ask you to convince the Turian to testify. Finally go and talk to the Turian and depending how you try to get him to testify will either result in +24 Paragon or +24 Renegade points. You can then leave the conversation and then open it again to repeat this process for more points.
I believe 5 Charm or Intimidate is required to be able to get the options to select during the dialoge.
"Keeper" locations
Citadel Tower 1 Near Chorban.
Citadel Tower 2 South, near the Council Chamber.
Citadel Tower 3 East.
Citadel Tower 4 Northwest, off in one of the side corridors.
Presidium 1 Western side, near the elevator to Citadel Tower.
Presidium 2 Northwest, near Wards Access.
Presidium 3 Northeast, in the small room to the northwest of C-Sec HQ.
Presidium 4 North, in the small corridor behind the Embassy Lounge.
Presidium 5 Northeast, Volus and Elcor Office.
Presidium 6 Southeast, near entrance to Consort Chambers.
Presidium 7 South, to the east of the Emporium near a set of stairs leading to the bridge.
Presidium 8 South; take the stairs on the south side of the Emporium.
Wards 1 Take the elevator down from the Presidium and you'll land in Flux and Wards Access. The Keeper is in one of the northern rooms in this quadrant.
Wards 2 Northwest, in the Alleyway.
Wards 3 Western side, in the corner of the Upper Markets.
Wards 4 Inside Flux, in the gambling room upstairs.
Wards 5 Near the elevator to C-Sec Academy. Take the stairs down from the Upper Wards and it'll be near Officer Lang.
Wards 6 Outside the Med Clinic.
C-Sec Academy 1 In the Requisition Officer's room.
C-Sec Academy 2 In Traffic Control.
Citadel Docking Bays You can access the Docking Bays through the C-Sec Academy.
Scholar Achievement Requirements
Council Races:
Asari - Council Meeting at start of Citadel
Salarians - Council Meeting at start of Citadel
Turians - Before Eden Prime or Council Meeting at start of Citadel
Extinct Races:
Protheans - Speak to Captain Anderson at start of the game (Before landing on Citadel)
Rachni - Speak to Avani near the Krogan statue in the Presidium
Non-Council Races:
Batarians - Speak with Captain Anderson and ask him about his past before leaving the Citadel Docking Bay (This is after becoming a Spectre. Choose "What Happened?" to hear the entire backstory)
Elcor - Elcor Embassy in the Presidium area (Next door to the Human Embassy where you begin after first Council Meeting)
Geth - Beginning of game, before landing on Edin Prime
Hanar- Emporium Salesmen in the Financial District of the Presidium
Keepers - Talk to the Avani right before the Citadel Tower entrance from the Presidium
Krogan - Overhear the argument between Wrex and Fist's Bodyguard in Chora's Den
Quarians - Follow main story to obtain Garrus and save woman in Medical Bay
Volus - Elcor Embassy (See above)