Water leaks, if caught & fixed are not the "horror" that many make them out to be. If you listen to some posters, ANY evidence of water means that the rig should immediately be totaled and dumped in a wrecking yard for parts. I disagree. EVERY rig will leak, somewhere, at some point. In fact, you will likely have a number of leaks, in various locations, over the life of the RV. As long as you catch them and seal them, it is no time to panic.
The rig looks very nice for it's age, and while it is priced high, it is not outlandishly high if everything checks out, IMO. Downside is if it is a consignment, there may not be much wiggle room on the price.
The slideout issue could easily be just that it wasn't fully brought in prior to the pic being taken (in other words, they could have stopped as soon as the top made contact); On my 2004, I must hold the slideout switch for 3-5 seconds after it is in/out to fully set the slide.