Sandro,
Slide extension/retraction works best when the coach is level, so always get level before putting the slides out.
The leveling system is quite similar to the one on my 2007 Tour Master and is made by Power Gear. All lights flashing at once is an indication of a controller error. Here are the error codes from the old Power Gear website.
https://www.google.com/url?sa=t&rct=...bd_dd5eIEYjtkw
I have had some issues accessing this site, so if you PM me an e-mail address, I can send you my PDF copies of the information. I also have a fairly generic coach manual from Gulf Stream that I can send
On my coach, the leveling procedure I use is this:
First I lower the air suspension (your gas coach probably does have this so just skip ahead...)
Then I raise the front of the coach by pressing and holding the Front button until the front comes up at least two inches.
You are correct that both jacks in the front are operated by this single button.
Next lower the two rear jacks by pressing and holding the Rear button. They don't always touch down at the same time -- don' worry.
Next add down force to either L or R rear jacks using their individual buttons (this is also how you get both rear jacks touching down in above step)
You will note that when you first began using the rear jacks that the front pair became valved together -- allowing them to accommodate side to side leveling but not drop the front height...
If your leveling unit is a semi-automatic some its operation may be slightly different.
I use an electronic level indicator to know how much to raise the back and what side is needing to come up to level side to side. As you have noted, you can only continuing lowering the jacks as individual rear units or the front as a pair -- when you retract the jacks they all come up at once.
Here is the level indicator I use which I place on the floor where it is easily seen from the driver's seat.
http://www.amazon.com/Camco-25505-EZ.../dp/B00DW954UC
Hope this helps...
Chuck