jQuery Grid Plugin - jqGrid

This is a great plug-in but I have a few questions.

I'm working on a site that uses many nested set trees that range from a handful of items through to trees with thousands of items. Currently I'm using treeView with jQuery but this gets incredibly slow as the number of items increases. Where it does work well is that I can add nodes, delete nodes, indent, outdent etc quite easily. I haven't come across any examples of treeGrid being able to add and edit like this. Is this something that I can easily implement?

Ideally I will be wanting a row of icons that perform these various adding and editing functions. The actual implementation of the code isn't an issue as far as affecting the tree data as I've made a php class to handle these functions.

In another implementation of jqGrid I cobbled together a similar grid with icons, but these were built in the php rather than in the grid script so I don't think it is a very graceful solution.

I am pretty much a jQuery novice so I appologise in advance if I need things to be spelt out.

A second question, is there a simple way to affect the css of a row based on returned results? I have type_id field that returns an integer indicating three levels of status. I was hoping to use this to change the colour of the rows.