Hi,

It begin to be a long time I worked on that module, and I don't exactly all the code.

For your first problem, try to put a higher weight to my module than the core attribute module in the system table.

My store works with 'total' uc_attribute_option_price_format, and it works, but I may have to change the weight as I said above.

for the second problem, I think it could have the same origin because the core attribute function make a += to calculate price, and in my module, I initialize variable to avoid this problem.

If you still have these problems after updating the module weight in the system table, give me feedback again.