Answer 1 : While there's no official answer, in our experience, you can transfer your H-1B even before October 1st when it's approved in August. No need for pay stubs from the previous employer, based on our experience.

Answer 2: If you never joined the employer, you won't have pay stubs, which is acceptable. Even if you join and leave the employer on October 1st without a paycheck, that's fine too.

Answer 3: Multiple employers are generally allowed unless they're connected or conspiring to manipulate the lottery, which is not allowed.

It is better to address these issues proactively rather than waiting for a Request for Evidence (RFE). While it's advisable to be prepared in advance, if an RFE introduces new concerns, you'll need to address them. However, this doesn't imply that the affidavits you prepared several months earlier will suddenly become problematic. If the affidavits are relatively recent, say one or two years old, it wouldn't be a problem.

Consider this scenario: If you had a spelling name issue and obtained one or two affidavits explaining it, and then the RFE raises this issue along with another one, you can simply provide supplementary documentation. The documentation you've already provided doesn't lose its validity just because the government posed additional questions.

In our practice, we only resort to preparing for a DNA test if it becomes the last resort because it can be quite expensive. I'm not certain about the exact cost, but we typically wait until the government explicitly asks for it.

A Canadian immigrant doesn't enjoy any special advantages over others. However, once you attain Canadian citizenship, numerous new opportunities become available. For instance, you become eligible for Treaty Trader and Treaty Investor visas like E-1 and E-2, as well as TN visas. Additionally, for most visa categories, you don't actually require a visa stamp. As a Canadian citizen, you can enter the United States without a visa, except for E visas and K visas. Visas such as F-1 and tourist visas typically aren't necessary; you can simply arrive at the border or airport with your Canadian passport. That's how the process works. It's important to note that being a permanent resident of Canada doesn't provide any advantage in the United States.

The processing time for the Canadian passport might be longer, so I suggest you check with the consulate. This situation appears unusual to me. In my understanding or recommendation, the law implies that once you take the oath of naturalization, it's the same as in the USA. I'm unsure about Canada's specific rules, but when you take the naturalization oath, you typically cease to be a citizen of any country except Canada. 

You may need to explore options to expedite your passport application, perhaps by paying emergency fees or any other required charges. I believe you should be able to enter the United States with a Canadian passport and an I-20 without needing a visa. Canadian citizens usually do not require a visa for entry.

Your employer is correct.