Here it is corrected. One thing about the time though; I assume you mean 9 a.m. to noon or 12 p.m. (not 12 a.m. midnight). If you do mean 12 a.m. just leave it as 12 a.m. or you could write it as midnight. Also, some people find it easier to write a.m. and p.m. as AM and PM. I think it looks cleaner. You can use them either way. "Dear XXXX, Thank you for the opportunity. I am available on Apr. 1 from 9 a.m. to 12 p.m. EST (local time in Boston). This is the best time to reach me on Skype. My Skype account is XXXX. I hope to chat with you on Monday. Have a good weekend." If you need anything else, feel free to ask.

Dear, XX: Thanks for the opportunity that you are giving me. I will be available on Apr.1, between 9 am and 12 am (Local time in Boston) That is the best time for me. My skype account is XXXX. I hope to chat with you on Monday. Have a good weekend! I think that is the correct way, anyway, I'm a spanish native speaker, so any english speaker can help you better! Regards!