The text on the Login Button is defined in the xx_YY.com_jfbconnect.ini file for your specific language. That's in the /language/xx_YY/ folder for your language. Most of the other social widgets automatically do translate, but the Login button does not.
As for the new user email, I just tried to register. The first time I filled out the JFBConnect registration form, I immediately got the following error on a blank white page:
Illegal key characters in global data
From a quick search, that seems to be an error from JHackGuard. I don't know about this extensions, but you may need to modify it to not interfere with JFBConnect as we do a lot of communication with Facebook, and changing that communication can cause problems.
I then tried to register again, and everything seemed to go well. I got the below email, which I can't read.. but hopefully this helps:
היי Alex Sourcecoast,
ברכות על הצטרפותך לקהילת הסקטצ'אפ העברית הראשונה!
אלו פרטי הרשמתך:
דוא"ל : -myemail-
שם משתמש : -myusername-
תודה ונתראה בפורום!
צוות Israel3D
קהילת הסקטצ'אפ העברית הראשונה
לתשומת ליבך: הודעה זו הינה הודעה אוטומטית מאתר אתר הבית של קהילת הסקאטשאפ הישראלית (www.israel3d.co.il).
I believe that's the CB new user email, but I could be wrong. Let us know.
Alex