Tips for outdoor group shots today, please!

[Fastchas]

Help me please?
I've been asked to do some photos of our Senior Management Team (around 10-12 people)on an away day today. Someone's got it in their head that I'm the man to do it after seeing a couple of fluke-ish shots I've done. Don't really want to turn it down as I'm new here!
Considering the fine weather and strong sunlight today, what would be the best set up for the shots;
Sun behind the group? Sun behind me (I understand this causes squinting so a no-no)?
Low or high aperture settings? Tripod with relatively slow shutter?
Or just stick it on Auto?
In my armoury I have a Tamron 18-200mm, a canon 50mm F/1.8 and a canon 28-80mm. Would the 28-80 be the best or would you use the prime at around f/8?
Sorry, but I'm still a bit Noddy at all this!

Thanks for any tips!

Edited by Fastchas on Tuesday 30th June 09:38

Edited by Fastchas on Tuesday 30th June 09:48

[Fastchas]

Thanks for the responses.
What is 'fill flash'?
I'm using a Canon 20d, is it using the onboard flash? (I dont have a mounted). Can I use it with exposure lock?

Edited by Fastchas on Tuesday 30th June 10:20

Edited by Fastchas on Tuesday 30th June 10:20