Can You Quickly Answer This Question About Mobile Games?

Yes, .jar and .jad are the kind of formats for Nokia mobile phones. Although Internet may not be the compulsory thing but depending on operator/manufacturer, most of such applications are usually used with Internet to avail full contents they offer. Viruses can be packed with such applications when you download them but java and symbian products are not always viruses, but no one can deny a virus get along with them if downloaded from somewhere least trustable like Pirated source which are usually not expensive etc.
As for www.gallery.mobile9.com I couldn't get anything unsafe about it. Although it gets too much annoying pop-ups but no bad review about it.