Ranking ccTLD in neighbouring country with same language? (belgium/holland)

I'm launching a new website soon and am still contemplating on which domain to use.
I'm from belgium, but also want to target holland. In Belgium there are about 5 million people speaking dutch. In Holland there are 15 million, so a much larger market and also much more monthly searches.
- Is there any disadvantage in using the .be (belgium) in terms of ranking in Holland?
- And while the language are officially the same, in wordpress they differentiate between NL_BE and NL_NL. Does that affect anything?
- In webmaster tools, do I select a target country or leave it open?