Dexcom G5 with xDrip+: OB1 collector? Native algorithm? Documentation?

Hi, I'm trying to use a Dexcom G5 with xDrip+ but I'm having trouble getting accurate readings (compared to finger sticks). I'm wondering if I'm doing something wrong, specifically:

1. Should I use the OB1 collector?
2. Should I use the native algorithm?
3. Are there other hidden settings I should/shouldn't use?
4. Where's the documentation? The main site has nothing and all I can find with google are posts related to other projects (and seemingly intended for audiences already familiar with xDrip+).

Anyone know? TIA!