Yes to all the above. I've used vodka and I've used brandy, and I prefer the flavor of the brandy. I cut my vanilla beans in small pieces and drop them right into the brandy bottle and leave them in. I've used it as quickly as a month later. I wouldn't add more brandy as what's there is used, unless I added more vanilla bean too. I do shake the bottle before using in recipes, I like the little vanilla flecks.
I've been doing this for years and I wouldn't use anything else. I heard that some of the Mexican vanilla that can be bought so cheap has something in it that's actually a poison. I don't know if this is true though and I never researched it because I never buy any form of vanilla other than the bean.