I'm not an expert on these but I did look into them a while ago. I always wanted a challenger and if the wife pushed out a baby, charger was the second option because of the extra doors.
The main difference between the RT and the SRT is 100 BHP and 75 ft lb of torque. RT has 375 ish BHP. You need to ask yourself, is that enough? Personally for me, it's plenty. There are limited opportunities to use it in UAE unless you're doing track days. Speed cameras every few hundred meters kind of defeat the purpose of fast cars.
There are no major reliability issues but build quality isn't the best. Lots of hard plastics and things screwed together by minimum wage workers in America who just want to finish their day and go for a beer.
I can't answer your questions about price. The market here is totally fake, prices are dictated by whatever the dealers feel like putting on their fake ads on dubzzle.
Another thing I'd like to add, just personal opinion though, I wouldn't get sucked into the whole GCC specs thing. Sure they were built and designed in USA but Texas in USA is just as hot as UAE so obviously they were designed to work in a similar climate. I know a lot of people will argue with me on this point and say GCC has bigger radiators and compressors etc but then done American cars designed to work near the equator have lesser parts? Surely the Americans will look after there own people rather than a handful of arabs?
Be aware though, because of the mentality of people here, the resale of US spec cars is less than GCC cars.
Also if you're buying a US car, check it on carfax website. You will get full proper history, unlike here.