Hi to you guys! Some newbie help please?

First I'd like to say Hi to you guys, I'm a new cat owner, just over 3
weeks and counting although my SO has had cats most of her life. If
anyone is interested you can view pictures of our new boys at the
following links

http://www.stevencook.net/images/benny.jpg

http://www.stevencook.net/images/chooch.jpg

We got them from our local Cats Protection in Scotland, UK. They are
8yrs old and are everything we'd hoped for!

The main reason for this post is that we have been feeding them IAMS,
and although the boys absolutley love the stuff I have been shocked by
some of the stuff I've read about their "research" techniques. Most
of the stuff I have read has been "old" and I'm wondereing if they
have cleaned up their act recently, if not can someone recommend an
alternate dry product we can switch them to?

Also, we live in a small one bedroom flat/apartment and are currently
trying to get them to use a covered litter tray with varying levels of
success.It doesn't half reek when they drop one! Does anyone have any
tips on converting them to such a tray?

Steve.