Re: Newbie, what racquet do I need?
Personally, I like the Aero Strike Cortex option better. I'm not a fan of oversize racquets, not even for beginners unless you need the power, so the midplus Aero Strike seems like a good option.
However, this racquet is head heavy meaning that the head is heavier than the handle. You may find some problems with that balance down the line, but for beginners it is a great racquet. I started with it as well.
As far as string type and tension, this is a very personal issue. The rule of the thumb is to start half way at the racquet indicated tension and adjust from there. I had bad results with the cheaper nylon (synthetic gut) strings and only use polyester and multifilaments. I prefer a nice polyester in the mains and multi in the crosses combo as I find that I can have the benefits of poly but not the stiffness.
Try stringing the mains with something like Babolat Pro Hurricane Tour and use Bablat Attraction in the crosses. If you can afford it, substitute the Attraction for Babolat Xcel Premium. Wilson Sensation is also a nice multifilament. If you don't like Pro Hurricane Tour's bright yellow color, you can switch to something like Head Ultra Tour.
The main idea is to have polyester in the mains and a multifilament in the crosses. You can play around with brands and gauges until you find something you like.