Call multiple hook inserts from different modules?
Rule of thumb: Don't call hook_anything() in other modules. :-)

If you call node_save($yourNode) then the node API will invoke hook_insert() in the module that implements that node type, if the node is being inserted. Otherwise hook_update() gets called for updates.

If you need to act on an insert for any type of node, and it sounds like you do, then you want to implement hook_nodeapi().

Examples has a node project and a nodeAPI project, so you can figure out which you need.