Huadu is a bit like a village compared to rest of Guangzhou. In reality you might as well treat it as a completely different place to Guangzhou.

Well, it ain't that bad (If you are in Xinhua and not some really rural place), but if you don't speak or read any Chinese you will struggle a bit. Also, don't expect a real Cantonese cultural experience because the vast majority of residents are migrant workers from Hunan (some residing illegally), which partially explains why some people are rather uncivilised there.

If you was referred to this job by 'findworkabroad.com', avoid it at all costs.

Also, there really isn't anywhere where you can attend Mandarin classes in Huadu as far as I'm aware. However, you will probably learn a fair bit because if you don't, you probably aren't going to feel comfortable anywhere around Huadu.