I've got thick carpet in my game room and find no issues, but I'm not someone who moves the machine a lot when playing.
Yes, that is quite old. Personally, I recommend the current beta code . . .
The last 'official' release can be found in the support section of our website.
I will say I have played a few very long games on Houdini in the last week as I've been looking to identify issues and correcting a few issues reported. Based on my experience I am not seeing 'mystery multiballs' that some have reported, so anyone who is on the beta, and is getting more than one ball kicked when they should not be in game play, should check their 'coil setting' on the release coils and try reducing it by one (release coils settings adjust 'duration' not 'power'). If you find balls are not releasing you can go back to what you had, if you are still getting two then adjust it again. Certainly possible there could be some path through the code that gets an extra ball, and I will continue to investigate.
As far as pitch, a higher pitch on the game can create a few issues, one it could result in an extra ball being released from the locks on occasion, so the adjustment above could be needed. It can cause a higher rate of stage rejects, it also typically requires you to increase flipper coil strength, which can increase the risk of air balls and broken plastics and puts more strain on the power system. It can also make the stage-alley shot hard to complete to the stage as the pitch will impact the trajectory of the ball. Increasing it a a little bit is fine, jacking up the back legs a lot is going to cause issues. Again, leg levelers all the way in, then level side to side (check both at lower and upper parts of the playfield). Then if you want a little more pitch, raise back legs a few turns.
If you are on the last official release, then you need to be sure the spotlights, backglass and back panel are all set to 10 in settings, otherwise you will have issues with extra balls being released. The beta code has quite a few changes to handle this less than desirable behavior of the system. The beta code also changes some activity around the magnets during multiballs to better balance power.