Replying to my own question I can report the following: I've made good progress and was able to move the date, and check amounts, and address to the proper locations. Here is what was most useful:

1. I changed the paper format to match the paper that you are using. 
2. To avoid the blank space at the top, it was necessary to edit the paper format (settings -> reports -> paper format), and set the top margin to 0 mm. (Not yet sure how negatively this will impact my other reports, but I was not able to overcome the margin issue  directly from the Qweb report). 
3. To position fields on the report, I found it was by far most useful to use CSS postion:absolute, for example,

               <!-- Check Amount, Numeric-->
               <span style="position:absolute;left:738px;top:139px;" t-esc="formatLang(o.amount)"/>

Now here are my outstanding requirements: 

a) I'd like to include line breaks in the address, before the city name. I'm finding the default code for the address difficult to read (the section after t-field-options):

<address style="position:absolute;left:62px;top:190px;" t-field="o.partner_id" t-field-options="{&quot;widget&quot;: &quot;contact&quot;, &quot;fields&quot;: [&quot;address&quot;, &quot;name&quot;], &quot;no_marker&quot;: true, &quot;no_tag_br&quot;: true}"/> 

b) I'd like to include the invoice number in the table under the description heading. I imagine this is a field that exists in o.line,  but I haven't been able to find the documentation that provides me with the descriptions of the fields. I found this source of documentation that may be the best spot to look: http://useopenerp.com/v8/model/pos-order-line, but I've not yet been able to find how to extract the invoice number from o.line. 

for information,there is a module to prink check at canadian format, see :

https://www.odoo.com/apps/modules/7.0/l10n_ca_account_check_writing/