Its cool until you have to finish the dex then it gets boring reeeeeal fast

It depends how you got it, if you cheated it there then it may not work, if you transfered it from a gamecube game then it should be fine

In the forest with all the duo battles, near the exit to the town with gardenia in theres a load of cuttable trees, cut and go through and its there, a load of murkrow should be there too

All of them but I'm not sure how to get the johto ones