When I send a money order to the U.S, it is from a Canadian bank. The bank has an association with an American bank and would indicate the American bank's name on the money order. This is common practice for major Canadian banks. I believe that under the American Uniform Commerical Code, in these circumstances, a money order from Canada is supposed to clear within 72 hours. If it doesn't, the problem is with the bank you took the money order to, not the money order. I am aware of a law suit going on right now where a Canadian bank is suing an American bank for violating this provision of the UCC, bouncing the money order to the detriment of their client after tehe date they were supposed to clear it.
Regarding shipping weight, if one company doesn't take packages above a certain weight, then others will.
In Canada, we pay taxes and brokerage fees on imported items. We may also pay customs duty. It depends on the country of manufacture of the item as to what the duty is, if any.
If a Canadian asks you to lie about the value of the item so that they can save taxes, they are asking you to commit a crime. Are you willing to pay a fine or go to jail if caught? It's your name and signature on the customs form with the incorrect information. The other person could simply deny they asked you to do it to save themselves. Not that what happens to them has any relevance to your guilt.
I've had people in the U.S. that I've purchased things from offer to lie about valuation in order to help me, without me even asking. I thank them but repsectfully decline and ask them to tell the truth on the customs form. Given who I am and what I do, I can't risk breaking the law. It would kill my job and career so I play it squeaky clean.