1) If it's your first time playing, going for TaN and Iro gives you more room to get up to speed. Not the best way to actually win the game, but it will give you a nicer feel for it. HR is nice to have, but only when you've learnt how to dodge. There's no "best skill" set up -- one can win the game with many different types of builds. Each build, however, has its own set of challenges and advantages. Personally, I prefer pistolling, but there are many others who love the shotgun. Up to your style I suppose.
2) The trick for hitting the big guys is simple: avoid getting hit. This means taking cover and striking at them one at a time from a safe distance. Chainguns are bad for the side-step-and-shoot technique due to the inherent inaccuracies of the weapon (chuck an Agility mod on it or take a level of EE), also, the master trait most suited for chainfire weapons (MAc) leaves one with little defensive options.
Lastly, you do not need to always kill every big thing out there: discretion is the better part of valour. If a YAAM is what you are aiming for, I recommend playing conservatively, and with your headphones on to hear where the monsters are.
The guides are not that outdated -- the lessons they teach are still very relevant. Meanwhile, have fun! (=
