What is Safe Time to Be Under Anesthesia?

It sounds like you have significant lung problems. You should discuss this with a Pulmonologist. My guess is that it would be safest to break up your goals into two smaller procedures. Also, sometimes just a tummy tuck can tighten the tummy enough to make it more difficult to breath (it raises the diaphragm). Be prepared.

The combination of tummy tuck, breast augmentation, breast
lift and liposuction can be performed in a single setting.  When these operations are performed together
safety has to be every ones first priority.

                Your
history of pulmonary problems and an estimated surgical time of over 7.5 hours
is troubling.  Under these circumstances,
it might be appropriate to modify the surgical approach.  Either utilizing a surgical team to shorten
the intro-operative time or performing multiple smaller procedures may be more
appropriate. 

                We
believe that the length of the procedure should never exceed four to six
hours.  Complications from surgery
increase significantly when these numbers are exceeded.  An experienced surgeon and surgical team that
focuses on efficiency can minimize the length of the surgical procedure.  We often use another surgeon as a first
assistant to help with the process.

                The
advantages of this approach are obvious and include improved synergy and harmony
which improves the overall aesthetic result. 
Patients experience one recovery rather than multiple recoveries and
they potentially save money when these procedures are done in combination.

                Combination
surgery isn’t for everyone.  Some
patients like yourself have coexisting health problems which may prevent this
approach.  Meeting with a board certified
plastic surgeon will help sort this out and help formulate the best treatment
plan for you.  In some cases, it may not
be appropriate to undergo cosmetic surgery.

7-1/2 hours for a young, healthy person to have the surgeries you are having sounds just about right to me.  Unfortunately, Murphy's Law even applies to cosmetic surgery at times.  I think your question is a good one to ask, and my recommendation is you give yourself a break, do the most important surgery first, maybe abdominoplasty and liposuction, recover for 6 months, and if all went great, go ahead and do the second surgery.  You didn't get all that loose skin and fat in one day, therefore you don't have to get rid of it all in one day.