I have used IKV 801 mini and tall attys, both the LR and HV versions. I found I prefer the tall 801 attys because I could literally flood them for lots of flavor and vapor and not get juice in my mouth. With the mini's, you have to be more careful.
When using adapters so you can used 510 threaded attys on your 801 native Woodvil, screw the adapter on to the atty first. You don't need it to be super tight. Just gently twist it on till it's snug. Then look at the bottom of the adapter. It should look like the bottom of a 510 atty. The center post should not protrude past the outside threads! It should be flush or a widdle bit recessed. You can usually adjust it with a little pressure, or sometimes with a small flat head screwdriver.
Edit: I just realized the above is for using 801 attys on 510 native mods. It doesn't apply to using 510 attys on 801 native mods.
Adapters are for advanced users, to be honest. My suggestion: Use your native 801 Woodvil with 801 attys and get a 510 native Woodvil, Grand, or Mini for your 510 and 306 attys.
I hope that helped. I realize I'm a couple of days late.