First I must say that alot of good people with balanced views have replied many a time on these forums and I now as one of them realise why I dont reply as much as I used too..... its because the same Q's keep arising.
Yes you can find the info here..... and time doesnt change things greatly here so no worries about the slightly dated info..
Your Q's answered:
Have read a lot about the organisation being in a mess and that crew scheduling isn't very pleasant. Management may be hostile as well.
Yes, expect to have frequent roster changes, but i am not on the 777 fleet. But all I can say is they just lost 40 777 staff of late so you will be doing max hours (like all fleets mostly...some more comfortably than others 
). It will take you for your training a bit quicker than non-type pilots, but still expect a couple months at least...and thats after you get here with all the paper work/visas/RP etc etc done.
Have also heard that the housing allowance isn't really adequate to live well. (in comparison with Emirates)
Correct. Housing prices in Qatar ARE A JOKE. its a manipulated market and unfortunately not a free true housing market so boo hoo to us.
Expect to pay around 12k for an average two bedroom at the Pearl, 15-18 for a 3 bedroom.
The company may have housing at some places, possible Ain Khalid gate, but its luck basis and availability.
Belkieve me the housing does not even compare to Emirates or The other nameless airline closeby.
If I have a choice between Qatar Airways and the other above mentioned.... I would definately NOT choose Qatar Airways.... it just cant treat the crews correctly with proper perks that match other airlines.
Does anyone know how much money one can save at the end of the month
considering that my lifestyle is simple and I have a wife and child with me.
If you are not blowing your cash on big loans and a bigger than normaly big villa then you could save $$$. As to the numbers, thats really up to you. 40% of your wage would be expected??
I have about 2000 F/O hours on the 777, what are my career progression prospects in Qatar.
Chances are you will be on the 777 fleet! They are not that stupid that they would put you on a 320! They might try but that would be the mistake of the incompetant staff they hire because they are cheap rather than investing in less staff with more competance! Simply either dont accept the contract or clarify it and point out the obvious to them.
You will be upgraded on the 777 most likely provided you meet the standards;pass the interviews etc
If I were to move to Doha it would be with my wife and baby boy. Is there a free and cosmopolitan society where they would be comfortable.
My god, do you realise that its not the West. But it is relaxed mostly for a M.E country. Its no Dubai though, but I like the smallness more than dubai but the standards here are very poor. Surface level, looks great, practically, bad. E.g. Maintenance: unless you either know the guy is qualified completely, then you most likely have to school them on what needs to be done. If they do it then there is a good chance its a rushed half arsed job.... indian style.... they same people that cook your food; build your houses; wire your house for electricity etc....
all I can say is one thing, the Villagio Mall fire. No body charged, none of the victims parents consulted after the event about charges or anything.... its that type of place. Relaxed, but so relaxed that they dont enforce alot of standards in the environment they live in, unless it suits them.....
out of sight, out of mind.
In terms of the company:
Nice enough, but very Trigger happy when it comes to "releasing pilots".... aka sacking them. Usually, there is a side to the story you never get told that makes QR look very aggressive...... but then again, with all the insane amount of SOP's and rules, its hard to remember them all. In terms of the flying side, if you break a rule intentionally that really puts safety at risk then you deserved to get sacked; but interms of minor and possibly moderate unintentinoal mistakes, usually there is retraining, but unless someone can comment, I have not heard of many going to retraining, some but not alot; simply that means that they are willing to not lose face and sack pilots even in the recruiting dilema they are in! Beware, but not alarmed. If you fly conservatively and take that extra minute or two then you will be fine me thinks.
Company stuff:
You dont really get much updated learning material; nor do you get much direction as to what to do/where to go. You get shown around quickly, and baby sat for the first week, but after that its generally start pulling your hair out dealing with no information, multiple phone calls only to find out different views every time or "i dont know".
CBT do not work on Mac's unless u have certain softwares.
The other handouts they give you are USELESS. They are outdated! And the IMHO ilegal. They should not even be handing it out.
some Phone numbers they give you dont have the proper numbers updated. There generally is no maps of the places you need to go.
No mailbox provided in the company anymore. And a shortage of PO.Boxes in Doha!
The I.T system is a bit of a joke. Over the top security; but I have a problem with multiple websites; all with a different password! Absolute pain in the butt. The Emirates system is WAY better!
They initially give you a default IBQ banking account; ironically it has ties with QR! You dont need this account, and are free to change, but when you first come to the country its almost a nightmare to not accept it. it ok as a bank though.
Medicals are easy if you can pass one at home you be ok.
Its a very proactive system. not many things come to you, you have to find it, depending on what your looking for it can be a royal pain. The entire system has to be streamlined and more efficient. I guess that they think the NDIA will fix all of this
All in all:
I like the smallness of Doha but it really does not compare to Dubai/AbuDhabi.
Its kinda a boring place; usually all your mates are busting there butt working when you have time off so its difficult to catch up with friends.
The company is ok, but has A LOT of room for improvement to make if they want to keep pilots (especially the 320 fleet). All this training backlogs should hint to them that something is not right here????
Great thing is the ID90's but this can be a pain on a quick trip away from Doha with the family.
People always think about the $$$ coming here, but remember the thing you can NEVER GET BACK is TIME. Dont waste it here if you are not prepared to have fits of frustration and anger, pleasure and balance that with fatigue 
Thats about it for now...... good luck in making a decision..... its not easy to live here, especially if you expect it to be as efficient as the western world, but if you have a decent attitude you can be alright.
I would suggest, like others is to come here for two weeks with the family; and see.
hope it helps.