Fior the rent prices you can have a look at these websites GNAds4U.com and Dubai Property Real Estate for Sale and Rent, Jobs in Dubai, Dubai Classifieds .
As far as I'm aware anyone is allowed to purchase a property in Dubai without any restriction but for the 99 years lease I think that it depends of the area where the property is located, I'm sure that it is the case in Mirdiff but for locations like Dubai Marina and JBR it is a full ownership.
Emaar, Nakheel and Dubai properties are one of the most serious developers.