If you want to learn the boxing techniques - train with boxers. There are gyms everywhere. The thing about martial arts is that its harder to learn without a live opponent. So much of it is
so relative to your opponents position, speed, stlye etc that learning from a book will only give you a glimpse of the depth and width of the techinique.
I've been training with boxers since i was six, and i'm still learning stuff. My dad, who is (at 56) great trainer and inspiration can still tag me when he tries real hard.
If u really want to learn hard, efficient hand striking techniques and upper body evasion, train with western boxers. The depth of tecnique, speed and power of western boxing is simply better than Thai Boxing - i dont want to start any flames here, but i've trained and fought with both, and and on the whole boxers punch harder, faster and more accurately than kickboxers. They train for it exclusively, the boxing stance is more suited to it (kick boxers sit to far over the rear foot for real punching power), and the techniquaes and combos are more diverse. Also, kick boxers dont really evade like boxers do. More stop kicking, high-forearm blocking etc.
However, if you want to integrate some hand techniques with your background in eastern, whole-body oriented MA, kick boxing is a great way to go. Its fun, hard as hell and very efficient. Also, elbows are devastating - simple and effective, easy to integrate with trapping. You wont learn those in any
reputable boxing gym.
Bags are good, but train
with someone who is a boxer/kick-boxer while using the bag - the bag is a great training aid if you're doing the technique correctly, but if your form is bad, you're just building bad habits into your muscle memory. My advice is, go to a gym.
just my 0.02c.
Cheers
Baoquan