July and August might get fairly rainy.
Weekend trips: the popular ones are the beaches (Boracay, etc), there are cheap local flights if you buy ahead of time. You can also head up north to Baguio, it's a nice place, though people usually travel there during summer (April-May)
Safety is a concern, yes, but don't let that stop you. Just be more wary especially if you're in a seedy-looking area. I think the Makati central business district is pretty safe most of the time.
Most people will have some level of English understanding, though some might respond to you in broken English. A few key phrases might help, but are unnecessary.
The basketball thing, hard to say, you have to know people who participate in leagues (the local term is "liga"). If you're working for a big company, the employees there will be able to help you, most guys are basketball fans.
Have fun and enjoy your stay!