The Chinese Language

Right now I'm learning Japanese, I don't know if I will, but I might start Chinese. I wanted to know what kind of differences there are between Chinese and English, besides the symbols. So far, from what I've herd, which is one sentence (XD), the sentence order is the same. Is that true? And in Pin Yin, or whatever, what are there numbers next to the words like "wo3 ai4 ni3" i think it was for "I love you". I'm interested because my friend speaks Chinese, but she just speaks it, she doesnt really know the grammer I guewss... Well, thank for all your help!

Tomii

Japanese grammar is about as different from Chinese as it is from pig latin. They have a lot of kanji compounds in common, but Japanese has a lot of compounds that don't exist in Chinese and of course vice versa. I don't recommend trying to learn them both at the same time. Either one is a big enough undertaking in itself.

I agree with JimmySeal
A chinese person MIGHT be able to understand some japanese sentences through the kanjis but will probably not be able to grasp the grammatical structure unless he's studied japanese.
As for learning chinese, well... you're probably gonna have lot of fun since it's entirely "Kanji-based". Regarding the pinyin system, it was introduced arround the 1980's to enable a transcription of real chinese. It's also one of the input systems to type chinese on your computer.
As for the numbers you're mentioning, there's 4 (+1) tunes in chinese (while there doesn't seem to be any tune in japanese).
To give you a common example:
ma1: mother 媽(mā)
ma2: sesame 麻(má)
ma3: horse 馬(mǎ)
ma4: to insult, to shout (at someone) 罵(mà)
ma5:question particle (like the japanese ka) 嗎(·ma)
So depending on how you say your sentence, the meaning will be completely different.