The Anaheim Hilton Suites are on the opposite side of I-5 and are certainly NOT within walking distance.
The Anaheim Hilton Tower is next door to the Convention Center across Katella from Disneyland. The easiest way is to cross Katella into the Timon parking lot. If this lot is in use you can walk across the lot to the tram station. If Timon is closed you'll have to walk along Harbor to the main entrance. Not too bad going but sure seems like a long ways walking back at midnight! I'd say 15minute walk from hotel to DL/CA entrance gates, 10 minutes if Timon tram is running. Faster if you're a kid!
Thats true but I have stayed there 3 times using Priceline for $48/night so the $15 parking is still a bargain. You can also get it for a bit more through hotwire.