Sorry can't help you there, most of my knowledge is about Queens. If your looking to buy, property values are insane in the good neighborhoods. Don't be surprised if a homes asking price is around 1 million. There a bunch of parks there, they are usually more of a dog run than a park though because of limited space. The following is a link for parks in BK. As far as pet boutiques go, they are all over but expect to pay more than you are in philly and the 8.375% tax rate.
There is also the Yorkie Power Play Group from meetup.com, I think they they have a membership fee though.
http://www.nycgovparks.org/sub_thing....html#brooklyn