I'm about to buy Fallout New Vegas but I'm reluctant to do so if achievements are still locked as soon as you hit Tilde.

Achievements are only locked for that session. When you exit the game and load your save again you can get achievements again.

So they're only locked for the seconds/minutes/hours after I opened the console (which won't happen very often) until I exit the game. That's very nice to hear, thank you

it only locks it if you actually enter soemthing in the console. Just exit the game, go back in and you are good ti go

Some mods require entering something into the console. So does the just-exit-the-game-rule apply if I use the console for modding purposes?