£10 gets you the whole handbrake gaitor with clips posted, or you can have just clips for £3 posted, There is a plastic frame inside leather which clips fit to, sounds like yours could be snapped.
Welcome to the LOC.
Wont work straight away you need an adapter,there are a few ways round it.
have a read here Thomas.
http://www.lexusownersclub.co.uk/forum/topic/81819-need-advice-on-fitting-new-head-unit/#entry816120
I have one and tbh i havent noticed any difference in performance or noise, the deciding factor for me was never having to replace filter again, just a wash and re-oil every year or so.
To find out, insert key in ignition and if security light goes out immediately its a master key, if there's a delay it's a sub key.
Hope this helps you out.
Firstly welcome to the club.
regarding your stereo
stereo removal
https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CDkQFjAC&url=http%3A%2F%2Fwww.lexusownersclub.co.uk%2Fattachments%2FRadio%2520Removal.doc&ei=A9hhUbpEw4Y4hI-A6AM&usg=AFQjCNFQCJ_keqn9350R3mQdneBQwjrz9g&sig2=t8k2Oe57xaFict2AS8qCvA
amp bypass cable and facia.
http://www.ebay.co.uk/itm/Lexus-IS200-300-Car-CD-Stereo-Facia-Adaptor-Amp-Bypass-ISO-Lead-Harness-/350749227652?pt=UK_In_Car_Technology&hash=item51aa487a84
and if you still want standard sat -nav, you need one of these.
http://www.ebay.co.uk/itm/lexus-is200-sat-nav-activation-module-/230958760877?pt=UK_In_Car_Technology&hash=item35c63703ad
or
http://beatsonicusa.com/beat-sonic-sla-91.html
You can get an adapter to get sat nav to work without standard h/u.
http://www.ebay.co.uk/itm/lexus-is200-sat-nav-activation-module-/230958760877?pt=UK_In_Car_Technology&hash=item35c63703ad
or
post number 6
http://www.lexusownersclub.co.uk/forum/topic/78790-standard-sat-nav/
another but not cheap.
http://beatsonicusa.com/beat-sonic-sla-91.html