Setting shipping for my items, is this right?

[goldenstonebazaar]

After reading most of major shipping threads here, everything got mixed in my head. Will you, please, check if this is right?

My shipping information in short:
I'm in Canada, and will be selling to US, Canada, Europe, Australia and New Zealand.
Packages are more or less the same, 5 oz average weight (0.3125 Lb).

1. Shipping costs:
- within Canada could be flat rate, $14 (have to refund closer provinces $4)
- US: flat rate, 2 methods of shipping:
Small Packet USA Air - $8.30
Tracked Packet USA - $16.50

- Europe - $9.50
- Australia, NZ - $10.50
If I select all these countries in drop-down list,
set flat rate for Canada $14, US $8.30 (it is not possible to add another method of shipping, right?).

Then, can I set in shipping matrix in 1 Lb column "0.3125" (of Lb, 5 oz), how? For 1 Lb package postage would be much higher (set by postal service, not my choice) and actual weight is not 1 Lb, this and shipping will be seen by buyer on PayPal label.

Then fill rows by names of European countries, one by one, same price for any of them, $9.50
Add two rows for Australia and NZ, with $10.50.
Only first column, under 1 Lb weight will be filled.

This should show to buyer from US or Canada flat rate, to International buyers only what set for them in shipping matrix, right?

2. Next, combined shipping:
The items will be combined by cost of the purchase for US and Canada,
- up to $73 base price, listed above, $8.30 for US and $14 for Canada
- $74 - $130 purchase it will be $16.50 for US (tracked method of shipping)
- one more gradation will be added for $210 purchase, need to pack, weight and find a rate late, likely above $20 (Tracked and insured method for above $100 purchases, insurance at my cost. We don't have a choice to add delivery confirmation, signature or insurance to first 2 methods of shipping, unlike in US).
How on the Earth should I do such combined shipping, if this is possible at all?
If it's not possible, how to enter in shipping matrix that there will be no combined shipping?

Sorry about long post,
Thank you.

[cosmicray]

Maggie will be the best to answer these, but I can add a little bit.

If you are in Canada, and you plan to ship via Canada Post (i.e. not close to the border where you can jump across to a US post office), then you must disable USPS Calculated. The only options available to you are the fixed price (at the bottom of each listing) and/or the shipping matrix.

[goldenstonebazaar]

Thank you, it was very helpful. I completely missed that part about USPS calculated overriding everything else. Already found the thread how to do that.
Now searching for 'synthetic weight' to learn more.