I'm afraid that I have to agree with Randy on both items. First, front brakes do most of the braking, and consequently have, on every car I have owned, worn out first. As stated, I usually go through two sets of front pads for a set of rear pads. If there is documented evidence that there is a problem with these cars, then you should have a warranty claim. Secondly, on my other two Lexus' (both RX300's), I've gotten about 65,000 miles on front pads, and could have gone a lot longer on the rears, but decided to replace both sets since I had it up in the air. I do all the work on these cars myself, and changing out brake pads is very straight forward.
On the curb rash, I think you should pass on the request to do an alignment. Today's cars are so stroutly built that it is very difficult to take one out of alignment. Normally, alignment becomes an issue simply because of mileage and the wear of the various bushings that are in the steering system. If you suspect damage to the suspension, you will note it in the handling of the car (i.e. tends to pull to the right or left consistently) or in tire wear, which will be uneven or premature.
Based on the two items included in your note, I would suggest trying another dealer in the future. Giving your current dealer the benefit of the doubt, he sounds way to conservative on his advice, which adds up to increased costs for the owner. On the other hand, he could be more interested in repairs than in the customer. I live in Chicago and have been impressed with the Lexus dealer I occasionally take my cars to, if I choose not to do the work myself. I think that my dealer if more typical for the Lexus mark, where they are trying to provide good and honest service to the customer.