Travel / Travel to Lwow from Rzeszow [18]

Hi,

I'd like to ask some advice on travel to Lwow. We're flying in to Rzeszow on a Friday evening in May, planning to travel across to Lwow the next day. A couple of questions:

1. What's the quickest/most convenient way to get there? I heard a good way is to take a train to the border then cross on foot and get a minibus, but I don't know how often the trains go and how long the whole journey should take.

2. When in Lwow, am I better speaking Polish or English? I don't want to invite a smack in the mouth.

Thanks

-Joe