It's not really possible to make the PS3 region free I'm afraid - there may be some sites which offer dodgy firmware to do it, but I'd say it's not worth the risk as (a) it could "brick" your PS3, making it unusable and Sony will not replace it since you've put non-official software on it - it will certainly void your warranty, even if everything works okay and (b) the next firmware update from Sony will replace it meaning you could never upgrade the firmware again and thus miss out on any potential updates in the future.
For other players, are you looking for DVD to be multi-region or both DVD and Blu-Ray? If just DVD, most of the common players from Panasonic, Sony and Pioneer can be made multi-region at no extra cost. If you're looking for multi-region Blu-Ray, this generally increases the price of the player. You can see some examples on
this site (NB - although I've used this site, I'm not necessarily recommending them as it was a long time ago!). However, I would put out that a lot of US Blu-Rays are also region free meaning multi-region for Blu-Ray isn't as key as it was for DVD. To find a list of all the region free releases, take a look at MovieTyme's website who independently check each title to ensure it is region free.
As for the PS3 not displaying HD sound on the receiver, this is because the PS3 is unable to bitstream (i.e. send natively) the HD audio codecs. What it can do is decode these formats onboard to multichannel PCM - so if you have the PS3 set to output as Linear PCM, this is what it's doing. So although the receiver does not display the format, you are still getting HD sound, it's just the decoding was done within the PS3 instead of within the receiver. You can easily check this by pressing Select when a movie is playing - the format that is being decoded will be displayed in the top right hand corner.