InfoPath Dev

It sounds like your form design may already be quite far along, but in this situation the most natural option would be to create a new form based off this XML format (in the Designer start page, one of the template types is "XML or Schema").  This would preclude you from adding fields to the main data source, but you would be able ...

Where have you placed your rules?  I'd suggest placing them on the CheckedFields tally field instead of the checkbox field.

The formula in this approach is a lot nastier, but there is a way to do date diff with a single formula and avoid that complicated rule logic: http://www.bizsupportonline.net/infopath2007/calculate-date-difference-infopath-rules-formulas.htm There's also the option of qRules, which makes date diffs (and a lot of other stuff) a piece of ...

Sounds like it's exactly what the error suggests - that the insert is causing a rule or default value to run repeatedly in a loop.  It's impossible to tell you how to fix this without seeing your form.

The problem here is most likely the presence of an xsi:nil attribute.  Search this forum for xsi:nil, and you should find plenty of help.

The reason the code isn't working is that the my: namespace in the XML you're constructing is different from the form's my: namespace.  Once that's fixed, a remaining issue is that the capitalization on your <my:DealerID> tags is incorrect.  Fixing those should make the code run correctly.

Are the month/year values in MM/yy, MM/yyyy, M/yy, yyyy-MM, or some other format?  Are they in a uniform format?

How about this: count(preceding-sibling::my:fieldname) + 1

Where are you using it?