Pretty Links for Multisite

Hello, I would like to know if pretty links is able to do the following:

Situation: I run a multisite installation with 4 linked sites in the network. For my user registration page, I would like to redirect all new user registrations to subsite A and use the signup form there.

User registration form in subsite A will have the URL: http://www.domain.com/subsiteA/signup
But I don’t want a visitor on subsite B to see that he is being redirected to subsite A.

Question:
1. Is it possible to use Pretty Links to change the registration form URL from http://www.domain.com/subsiteA/signup to http://www.domain.com/signup ?
2. I see from the screenshots that there are options for parameters: is the default to use standard parameters or no parameters forwarding? What are parameters for? Sorry, tech noob here >.<
3. Will this affect SEO or something? Especially because a large number of users are from China and China has their infamous firewall. Will using this cause my site to be blacklisted or the links to not work?
4. I use WPML to create a bilingual site. So if I use Pretty Links, do I need to change the URL of both languages or just change the URL for the webpage in the default language?

Thank you