Also do I need to a) show a check box option to user b) whether it can be pre-checked or not? Country specific replies will be much appreciated.
First you'll need to determine the legislation in place surrounding anti-SPAM acts and whatnot. In the US that's the CAN-SPAM Act of 2003: http://en.wikipedia.org/wiki/CAN-SPAM_Act_of_2003. There's much detail that you need to to research for just the US alone, in addition to the additional countries.
Second, is your target market really that globally diverse at this stage of your company? I'm making a few assumptions here, but my thinking is that you could reduce legal startup costs here by honing in her target strategies first.
I also found this related Clarity question which provides some excellent further insights: https://clarity.fm/questions/1728/is-sending-unsolicited-commercial-email-to-b2b-customers-violating-can-spam-if
Hope this helps :) Again, I think the best advice I could give you is to target down your markets to keep these initial costs down, and go from there. Feel free to reach out at anytime if you'd like to chat further.
When a user signs up to access your website, you can include an opt-in checkbox that is pre-checked. It should say something like, "Yes, I would like to subscribe to X company's newsletters." Pre-checking the box is ok, because it still gives them the choice to un-check it.
Regarding needing information from the different countries...if you mean you need to know what country they are in; you could use a simple dropbox box at signup. If you need to ask different sign-up questions based on their country of origin, you could use a conditional logic form. If they select EU, different questions may appear; select Canada, maybe the postal code entry is now formatted differently than for US.
I would suggest looking at Gravity Forms. Feel free to contact me on Clarity for any follow-up questions.
From the US- How are users signing up to access your website? And why would a user sign up to access a website?
If users are completing a form to receive access to your website, are you communicating to them that they are also opting in to your newsletter?
If they are completing your form to access the site only, then you could include a checkbox at the bottom for them to select if they also wish to subscribe to your newsletter. You could also include an opt-in option if you send a confirmation email from the site access form.
I am a strong proponent of creating optimal user experiences. Auto subscribing someone to something may be OK as long as they know. However, I would always prefer to allow users to choose their own adventure.
Hope this helps.