You can use the checkbox formatter to display a cell as a checkbox. As part of the colmodel:

// A checkbox that is read-only until the user edits the row

{name:'my_checkbox',index:'my_checkbox', editable:true, 

 edittype:checkbox, formatter:'checkbox' }



// A checkbox that may be edited at any time

{name:'my_clickable_checkbox',index:'my_clickable_checkbox', sortable:true, 

 formatter: checkbox, formatoptions: {disabled : false}, editable: true,

 edittype:checkbox}

As for the dropdown, you can pass a custom format function to the editrow function:

jQuery('#mygrid').editRow(id, true, formatEditors);

Then, inside this function you would want to create a SELECT (or whatever dropdown you need):

function formatEditors(id) {

    // Your drop down code here...

    // EG: jQuery(#+id+_myDropDownRow,#mygrid).

}

So when you edit the row the data will be displayed in a dropdown.