SMD equipment

I need to remove and replace some square SMD chips and was wondering what tools are best for the job. I see a lot of stuff from China. I am looking at a Atten 850D. it is the big handle with a strong hot air blower. Not the pencil type. I have one of those and it doesn't seem to work on large chips. Will 850 do the job and what else do I need:? Do I need special flux paste and special solder? Do you need a preheater for the board. What other tools are needed. Especially when trying to install a replacement chip. Any other things to look out for? Also I see this equipment selling along with mobile phone parts and stuff. What is the connection? Is there that big of a demand for Mobile phone repair that they would need to purchase $1000.00 of dollars worth of equipment. Wouldn't they just throw them away. Or are they doing something sneaky with these tools. Thanks Russ