You can return your system, un-styled/cut if you have an issue with it.
How long does a system last? How long is a piece of string? Can`t give an exact answer as there are too many `variables`in the mix....how your `treat` it, where you live [very hot sunny climates will affect/oxidise hair quite fast [you can use leave-in conditioner with sunscreen] Generally a lace system [with reasonable care] can last anywhere from 3 -6 months.....I had one which I got 10 months out of..just `depends`.
Synthetic hair reflects light differently to real hair and is not as realistic -looking, generally.
For work-outs etc...nothing has to be `done`to the hair but you will need to use stronger bonding materials to cope with excessive sweating....the acids in sweat will attack/damage any base material over time so make sure you rinse sweat out ... doesn`t mean you have to shampoo the system...just plenty water to dilute down the sweat. You will probably have to do more frequent bond-replacement if you work-out frequently, as sweating/moisture/high body-temperature will affect tape/glue...there are many thread/posts down along the forum regarding exercising etc. so have a look down along there. Have a selection of tapes and at least 2 glues to start you off until you find what works best for you...again ..there are older threads where people have been given comprehensive `start-up`lists of cleaning/care products to order to get them going.... cheers. Paul.
p.s. I remember your first thread/pics..just had another look at them there... I think full-cap would be your best option as your sides/back are so thin...... I`m gone fullcap since only this summer as I was just unable to get a good blend onto my side hair as it was just too thin.....the pic of the guy you posted on your other thread there ...well that style can be achieved pretty easily but my advice would be to go fullcap......normally I`d tell any young guy to start off with a topper, but you`re limited by what you have remaining...it must be tough on you, but with a decent system you`ll look a million dollars.