Mate, I'll get this in before the sabre-toothed do!
You'll get torn apart for using text-speak and lazy typing such as "iv" when you mean "I've". A big part of selection is presentation - think about being an ambasador for yourself - and your initial impression counts for a lot.
Secondly, a lot of your questions seem rather broad, which suggests a lack of research. I'm sure that a couple of hours with Google, a good newspaper and the PPRuNE search facility could enlighten you. Again, a cynic could use such broad questions to infer a degree of laziness in your research.
To answer one of your questions, however, I would say that you need to think for yourself about whether you consider certain aspects of the service life as "bad points" or just challenges. For example, during training you can expect to move often, which can place strain on your social life but offers the opportunity to see parts of the UK you otherwise may not have visited. Every cloud, and all that...
Blunty