At what rep level can I get a faction quest in Destiny

What doesn't carry over (becomes a normalized amount)

• Base defense
• Base weapon attack

What does carry over

• Weapon progression (including damage bonuses)
• Armor progression (Including Defense bonuses)
• Abilities
• Character progression (stat upgrades)

This means that even though they are on relatively equal starting ground. A Level 20+ will have an advantage over a level 5, but not so much that the low level doesn't stand a chance.

The stats of the items for each faction has differences.

One strategy is to figure out which faction has the piece of equipment you most want and work on that faction. For example only Future War Cult and Vanguard have Hand Cannons, so if you want one of those you can decided between them.

You should also be aware that while wearing their colors you'll turn Vanguard and Crucible faction reputation rewards into the faction rewards you chose. You will not turn Crucible or Vanguard marks (the currency) into faction marks.

You can't turn Vanguard Marks into Crucible Marks. Faction items (except Vanguard) can only be purchased with Crucible marks.