Adding vanilla, cacao, brandy and rum?

I would soak the beans and the cacao nibs separately rather than together. That way you can add according to taste individually. Otherwise, if your ratio is off you are screwed.

 

Vanilla and rum play nice. I can't speak for the apple brandy, I don't like calvados.

 

I never soak my nibs (average 10-16 oz nibs per 5 gallons) and get excellent chocolate flavor from them by just "dry nibbing" for 10-14 days. I've found that putting them into a drawstring hop bag gets more surface area interaction and better overall depth of flavor. I keep different varieties of vanilla bean tinctures (2-4 vanilla beans chopped and scraped in 4-5 oz liquor) going all the time to have them handy and the longer they sit, the better they are. You aren't going to get much flavor from the spirit used unless it's a very small batch...so be it apple brandy or rum, the liquor will not attribute any character to the beer overall. If you use oak though, you will get flavor from whatever liquor you soak it in, but oak is a different monster all together. Depending on if you use chips, cubes, rods, staves or whatever, you will have different aging times to get the oak character you want. Overall, the more oak surface that is exposed to the beer, the faster and more oak character you'll get. So chips will give a stong oak flavor much faster than using rods for example. Be careful with oak because you can go overboard very quick before you realize it! 1 or 2 days extra on oak can sometimes make a HUGE difference in the final beer.

 

My mileage varies from @DrMindbender experience with spirits. When I use rum to soak my vanilla beans I can pick up the rum flavor in the final product. It comes across like creme brulee. Not the shitty beer though, the good dessert.