Please may I have some help:

I recently bought flights in the current BA sale, but the carrier/operator for all flights is Qatar. I have my BA PNR and confirmation email all OK.

Route, in case this matters is LHR - DOH - PER, return.

I understand to book my seats I need a different PNR, QR's one, not BA's. But how do I go about getting this? Do I need to phone somebody, somewhere? (I hope it's not BA, but might be!)

We fly in QR business, QSuites all the way. I have previously seen some tips on choosing seats, aircraft dependent, for couples - knowing of course we will essentially fly all the way in blissful isolation with which we are happy and accustomed with other carriers, but this will be a first trip on Qatar metal. Please may I have a link to the most useful FT wiki for choosing our seats?

Oh, food and drink of course, while I'm here. Plus lounges. I've been reading the QR website, but any links for advice, tips, experiences would be appreciated. Better still, personal tips very much appreciated from this well travelled community.

I will be looking at Youtube as well in due course as that's such a brilliant resource as well, but I do love personal input from real people, and will be very grateful for any other personal advice, comments and anything else to ensure we have a great experience - we've heard so much about Qatar but the opportunity to fly them has never come up before now.

Thank you all in advance.