subscribe by email, how to change language and edit responses

Hello Friends

I am new to the subscription. A few questions:

1) I signed for the monthly subscription because i am not sure if i want to continue. For what i have seen you have made an excellent work. I will consider soon to upgrade to annual, is this possible, right?

2) About subscribe by email plugin.

2a) Since there are a few things that are in english and i need it in spanish, like the “read more” option or other notes like:

You are subscribed to email updates from Yoga Sampad

To manage your subscriptions, click here.

To stop receiving these emails, click here.

etc…

Where can i change it?

2b) How many emails can i import via CSV? My list is quite big, 27.000 emails. which are the fields needed to import it? Just the email?

2c) i have a dedicated server for sending these emails, how the pluging sends it? via the SMTP, local host or how?

Thanks !!