I'd take the 16-45mm for your wide to normal shots, plus the 100mm for macros and candid telephoto shots. The 12-24 would be useful too, but you don't want to be carrying too much. It's a tiring and crowded place. If you start feeling claustrophobic, Chelsea Physic garden is nearby and well worth a visit.

Are you going to take an 18-55mm to cover that range?

You can only assume that people who say tings like that spend all their time comparing images at 100% on a computer screen, rather than taking and printing pictures!

That photo with the pearls is absolutely stunning Tim, great concept and execution.

Rover - any lens will allow you to manual focus, just change the switch on the camera body. If you're starting out you could grab yourself a manual focus Pentax-A zoom, like the 80-200mm. That'll force you to practice manual focussing skills, and only set you back thirty quid or so....

That could be it... above ISO1600 the colour certainly becomes increasingly muted! Other than that, experiment with the colour settings and have a go at customising them if you like.

I used to have an istDL2, with the same sensor as the K100... I came across some old 'straight out of the camera' jpegs the other day, and was impressed with how punchy they were!

It looks like your ka adapter isn't quite working. You should have the aperture appearing in the viewfinder. (Presuming the lens is set to the A setting or whatever the equivalent is!) Try cleaning the contacts, if that doesn't help, disengage the lens in the mount, and then very slowly turn it back into place. It may start working just before the lens clicks into place.

You may want to try manual mode with the green button metering instead.

Re focal length, input the one you'll be using, or if you plan to use lots of different focal lengths, input the smallest one. Better the shake reduction is less efficient than over compensates.

It must be the sensor as the K7 has less CA with the same lenses. Perhaps the others correct for it automatically.

However... I think the CA in the OP's shot is from shooting a bright reflection with a fast lens wide open.

Well the kit lens's dof will be deeper than the 70mm at f2.4, but at the same settings the 70mm should be sharper, unless something's wrong with it.

Sounds ike you have had some very bad luck / not chosen the best supplier, and are also suffering a nasty case of 'buyer's regret' - an affliction I also tend to suffer from. It's a feeling that soon goes away when you start taking 'real' pictures and get to know your new camera better.

Re the replacement K5, Clifton Cameras are advertising 'guaranteed stain free' 2011 stock on their website. I bought my K7 from them - clean as a whistle. It sounds like you were fobbed off with a camera someone had already returned.