Real Estate / Building Land - Advice required [4]

I know countless questions get asked regarding land on this site, but I would appreciate any help regarding the following.

Upon recent visit I have been offered a parcel of building land close to where my relatives just outside Krakow. They seem to think it would be a straight forward purchase from their friend and again straight forward with the build process.

I was hoping if anyone could give me any helpful advice on:

1) what to look in to before commiting
2) if any red tape may prevent or hold up the purchase.
3) I am aware I will need a english speaking solicitor, anything else
4) are there any tax implications too.
5) could any finance be raised via a Polish bank for the build.

Thanks for any advice/help given.