HI,
Regarding the pictures, they will put stills up on the screen at the end that you can take a picture and get a good angle. So don't worry regarding that.
The transvaginal scan and 'swab' are only offered at 20-22weeks scan,
and it will probably nicer for you to be prepared as I wasn't! They will ask you to take part in research at 12 weeks scan as well. So just be ready so that you can make the decisions right for you.
My problem with it was that they were very pushy, and I had no prior warning about an invasive procedure (or a good explanation). The sonographer was very 'short' with me when I said no and tried to push it for my entire scan! Completely ruined the experience. Maybe if you say 'no' then they are pushy. DP was also very upset with how they treated me!
The leaflet says you should be able to discuss options with your GP prior to the appointment, but this was impossible as I was not told about transvaginal scan and swab (I really didn't want the swab as they said it was like a smear and I passed out last time I had a smear!) until I was having my blood pressure taken 2 mins before the scan. They literally gave me no time to think!
I really wish they could have informed us better before the appointment.
Saying all this, my 12 week scan was much more pleasant than 22 week. They were still not happy I refused research but nicer about it. So I may have been unlucky with my sonographer(s) at 22 week scan.