2
this can be done by few modules:
myAlbum 2.84 (Gallery module)
xcGal 1.1 (doesnt have description)
XOOPSGallery 1.3.3.5 not work well with apache 2.0.52/.53 with PHP-Accelerator (the bug still doesnt have sollution and fixes)
Search can be done with Google2 module, u can download it from modules resporsitory.
Counting users sells (posts) is easy , it can be displayed from xmemberstats-2.1 (Malaysia XOOPS Community).
Also u can try the IFramed version of osCommerce, cos the XOOPS Shop will be under construction for a long time, but is not recommended to use it on a production sites.