I can share my Mandarin experiences with you, as I have been in Taiwan for almost 7 years.
First, some of the Canadian Diplomats that go over to China spend 2 years and 40 hours a week learning Chinese, I am not sure if homework is on top of that. They do this in Canada, but when they get over here it is a whole different game. IMO learning Chinese is clearly a lifelong commitment. There are also programs here that cost $$$ where it is 2 straight years of classes and homework, but you are supposed to be fluent after that.
Learning English as a Chinese speaker isnt nearly as hard as our alphabet is easier to master, they have tones and characters and it can be very difficult. I took classes for my first couple years when I lived in the country, but have lived in big cities here for the past 5 and get by easily on English.
I know there is alot of hype to be learning Chinese but after being here I just dont see it as top execs here are all educated in the US, and you can hire employees here for $12,000 CAD/year that lived in an English speaking country for 5 some years that can communicate well in English, Chinese, and they would probably know at least one other language pretty well.
You can goto the website
www.forumosa.com and connect with Foreigners here studying Chinese and ask all kinds of questions. And get Skype, you can do a language exchange with someone in China and it would take you 5 minutes to find someone that would practice with you.
One more example is that it takes kids until grade 9 to learn all the characters and most of their school days consist of learning Chinese and the characters and writing practice for hours and hours, not to mention they goto school here all day 7-4 (i think) and then goto cram schools after to do their homework for a couple more hours.....it is really a lifelong commitment to learn the language plus the culture is a whole other story.
But in the end if you had those language skills it would defintely help you out in the long run, one more thing there are different dialects all over China, when I go to HK or China they can't understand my accent as you will have a foreigner accent (and I have a Taiwan/foreigner one) and won't ever sound like a native speaker that is why it would be an absolute must to do a language exchange over Skype to reduce that.
Rosetta Stone is also supposed to be the best program out there.
I hope this helps!!