1 -"send/receive" does indeed log-in but that does not affect your web based consultation of your mail.
2 - I know that is a problem. Even though you send them in the body of your mail, many, if not most of the web based mail will put it as an attchement in the case of a picture. They probably will keep your Word generated text, as it sees it as text but anything graphic will be converted to an attachment. Experiment sending documents to a web mail, if you have one yourself or of a friend and check how it arrives.
Hope this helps, and, I see absolutely NO reason to use webmail, a client has soo many advantages and ease of use, and if you get your own domain you are no longer married to the ISP for your addresses, you take them with you when you change, simple procedure to be requested and done by the ISP